Add cudf::strings::compute_regex_state_memory API

[davidwendt]

Add an API that returns the size of the state memory required to execute a specified regex pattern over a strings column. This is to help callers manage expected memory resource requirements for calling strings APIs that use libcudf's regex engine.

[codecov]

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[jlowe]

From an API perspective, lgtm. The RAPIDS Accelerator can check for excessive memory usage or diminutive concurrent rows to decide when to avoid performing the regex processing on the GPU.

[ajschmidt8]

Approving ops-codeowner file changes

[mythrocks]

Some minor nitpicks, but nothing over which to hold this PR.

[davidwendt]

I'm going to close this based on this comment: #10808 (comment)
We can reopen this later if it becomes necessary.