Use offsetalator in cudf::strings::split functions

[davidwendt]

Description

Adds offsetalator in place of hardcoded offset type arrays to the strings split functions:

• cudf::strings::split()
• cudf::strings::rsplit()
• cudf::strings::split_record()
• cudf::strings::rsplit_record()
• cudf::strings::split_re()
• cudf::strings::rsplit_re()
• cudf::strings::split_record_re()
• cudf::strings::rsplit_record_re()

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[davidwendt]

Some performance degradation in long strings to be addressed in a follow-on PR.

# split

## [0] NVIDIA RTX A6000

|  row_width  |  num_rows  |   type    |   Ref Time |   Cmp Time |        Diff |   %Diff |
|-------------|------------|-----------|------------|------------|-------------|---------|
|     32      |    4096    |   split   | 353.942 us | 347.504 us |   -6.438 us |  -1.82% |
|     64      |    4096    |   split   | 413.765 us | 406.981 us |   -6.784 us |  -1.64% |
|     128     |    4096    |   split   | 497.669 us | 491.159 us |   -6.510 us |  -1.31% |
|     256     |    4096    |   split   | 608.428 us | 602.191 us |   -6.237 us |  -1.03% |
|     512     |    4096    |   split   | 844.322 us | 844.510 us |    0.189 us |   0.02% |
|    1024     |    4096    |   split   |   1.164 ms |   1.165 ms |    0.348 us |   0.03% |
|    2048     |    4096    |   split   |   1.669 ms |   1.680 ms |   10.412 us |   0.62% |
|     32      |   32768    |   split   | 469.089 us | 464.069 us |   -5.021 us |  -1.07% |
|     64      |   32768    |   split   | 445.271 us | 445.741 us |    0.470 us |   0.11% |
|     128     |   32768    |   split   | 557.610 us | 557.831 us |    0.221 us |   0.04% |
|     256     |   32768    |   split   | 732.601 us | 747.264 us |   14.663 us |   2.00% |
|     512     |   32768    |   split   |   1.075 ms |   1.109 ms |   34.260 us |   3.19% |
|    1024     |   32768    |   split   |   1.517 ms |   1.588 ms |   70.731 us |   4.66% |
|    2048     |   32768    |   split   |   2.234 ms |   2.392 ms |  157.516 us |   7.05% |
|     32      |   262144   |   split   | 650.987 us | 660.003 us |    9.016 us |   1.38% |
|     64      |   262144   |   split   | 767.996 us | 796.298 us |   28.302 us |   3.69% |
|     128     |   262144   |   split   |   1.797 ms |   1.874 ms |   76.762 us |   4.27% |
|     256     |   262144   |   split   |   2.037 ms |   2.187 ms |  150.323 us |   7.38% |
|     512     |   262144   |   split   |   2.535 ms |   2.849 ms |  313.964 us |  12.38% |
|    1024     |   262144   |   split   |   4.036 ms |   4.672 ms |  636.598 us |  15.77% |
|    2048     |   262144   |   split   |   7.722 ms |   9.088 ms |    1.366 ms |  17.69% |
|     32      |  2097152   |   split   |   1.926 ms |   2.099 ms |  172.113 us |   8.93% |
|     64      |  2097152   |   split   |   3.008 ms |   3.324 ms |  316.418 us |  10.52% |
|     128     |  2097152   |   split   |   8.832 ms |   9.411 ms |  579.038 us |   6.56% |
|     256     |  2097152   |   split   |   9.553 ms |  10.755 ms |    1.202 ms |  12.58% |
|     512     |  2097152   |   split   |  13.492 ms |  15.873 ms |    2.382 ms |  17.65% |
|     32      |  16777216  |   split   |  11.942 ms |  13.140 ms |    1.198 ms |  10.03% |
|     64      |  16777216  |   split   |  21.172 ms |  23.314 ms |    2.142 ms |  10.12% |
|     32      |    4096    |  record   | 266.254 us | 257.481 us |   -8.773 us |  -3.30% |
|     64      |    4096    |  record   | 274.727 us | 265.579 us |   -9.148 us |  -3.33% |
|     128     |    4096    |  record   | 285.355 us | 275.869 us |   -9.486 us |  -3.32% |
|     256     |    4096    |  record   | 310.321 us | 302.704 us |   -7.617 us |  -2.45% |
|     512     |    4096    |  record   | 281.551 us | 279.880 us |   -1.672 us |  -0.59% |
|    1024     |    4096    |  record   | 309.191 us | 310.298 us |    1.106 us |   0.36% |
|    2048     |    4096    |  record   | 375.990 us | 384.850 us |    8.860 us |   2.36% |
|     32      |   32768    |  record   | 277.552 us | 270.440 us |   -7.112 us |  -2.56% |
|     64      |   32768    |  record   | 298.828 us | 296.294 us |   -2.533 us |  -0.85% |
|     128     |   32768    |  record   | 351.183 us | 349.425 us |   -1.758 us |  -0.50% |
|     256     |   32768    |  record   | 445.231 us | 450.598 us |    5.367 us |   1.21% |
|     512     |   32768    |  record   | 410.295 us | 434.163 us |   23.868 us |   5.82% |
|    1024     |   32768    |  record   | 553.866 us | 619.496 us |   65.629 us |  11.85% |
|    2048     |   32768    |  record   | 836.477 us | 967.847 us |  131.369 us |  15.71% |
|     32      |   262144   |  record   | 417.883 us | 419.429 us |    1.546 us |   0.37% |
|     64      |   262144   |  record   | 579.503 us | 597.616 us |   18.113 us |   3.13% |
|     128     |   262144   |  record   |   1.151 ms |   1.220 ms |   69.452 us |   6.03% |
|     256     |   262144   |  record   |   3.584 ms |   3.711 ms |  127.473 us |   3.56% |
|     512     |   262144   |  record   |   1.451 ms |   1.737 ms |  286.181 us |  19.73% |
|    1024     |   262144   |  record   |   2.585 ms |   3.165 ms |  579.501 us |  22.42% |
|    2048     |   262144   |  record   |   5.181 ms |   6.565 ms |    1.383 ms |  26.69% |
|     32      |  2097152   |  record   |   1.435 ms |   1.582 ms |  147.143 us |  10.25% |
|     64      |  2097152   |  record   |   2.665 ms |   2.928 ms |  263.861 us |   9.90% |
|     128     |  2097152   |  record   |   6.408 ms |   6.940 ms |  531.913 us |   8.30% |
|     256     |  2097152   |  record   |  22.797 ms |  24.032 ms |    1.236 ms |   5.42% |
|     512     |  2097152   |  record   |   9.999 ms |  12.341 ms |    2.342 ms |  23.42% |
|     32      |  16777216  |  record   |   9.790 ms |  10.887 ms |    1.098 ms |  11.21% |
|     64      |  16777216  |  record   |  19.703 ms |  21.746 ms |    2.044 ms |  10.37% |

[davidwendt]

/merge