Deprecate cudf::make_strings_column accepting typed offsets

[davidwendt]

Description

Deprecates the following factory functions:

std::unique_ptr<column> make_strings_column(
  cudf::device_span<char const> strings,
  cudf::device_span<size_type const> offsets,
  cudf::device_span<bitmask_type const> null_mask,
  size_type null_count,
  rmm::cuda_stream_view stream,
  rmm::mr::device_memory_resource* mr);

std::unique_ptr<column> make_strings_column(size_type num_strings,
  rmm::device_uvector<size_type>&& offsets,
  rmm::device_uvector<char>&& chars,
  rmm::device_buffer&& null_mask,
  size_type null_count);

The first one is not needed, rarely used, and inefficient. The only callers found can use other, more efficient functions which do not require copying the device data. The 2nd one is only used in 8/150 places and can be easily recoded in place to use type-erased factory function instead.
Removing these APIs helps reduce the number of functions that require type-specific offsets to make it easier to support offsets of larger types in the future.

Checklist

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

[vuule]

Looks good, just some follow-up questions

[vuule]

is there any need to have actual CHAR data type in cudf?

[davidwendt]

No. Because we would just remove it with PR #14202

[vuule]

I was thinking outside of the context of strings columns. Just a char column as such.

[davidwendt]

I cannot think of a reason to have one outside of strings.
I fear it would create issues in how the column data is interpretted/encoded.

[davidwendt]

@GregoryKimball asked me to cc @etseidl on this PR in case you are using these APIs in any current pending work.
The deprecated APIs will likely be removed in release 24.04.

[etseidl]

The deprecated APIs will likely be removed in release 24.04.

Thanks for the heads up...I believe I looked at this PR earlier and didn't think there'd be any problems...I'll do a closer look in a bit.

Edit: I only seem to use

std::unique_ptr<column> make_strings_column(size_type num_strings,
                                            std::unique_ptr<column> offsets_column,
                                            std::unique_ptr<column> chars_column,
                                            size_type null_count,
                                            rmm::device_buffer&& null_mask);

so I'm good.

[davidwendt]

/merge