Simplify Transpilation of $ with Extended Line Separator Support in cuDF Regex

[SurajAralihalli]

Resolves #11554, #7585

In cuDF, support for multiple newline characters was expanded from NEW_LINE (\n) to include the following:

• NEXT_LINE (\u0085)
• LINE_SEPARATOR (\u2028)
• PARAGRAPH_SEPARATOR (\u2029)
• CARRIAGE_RETURN (\r)
• NEW_LINE (\n)

PR #17139 introduced this change to cuDf JNI with RegexFlag::EXT_LINE. This PR simplifies the transpilation of $ by changing the pattern from (?:\r|\u0085|\u2028|\u2029|\r\n)?$ to the simpler (?:\r\n)?$ and updates all functions to use RegexFlag::EXT_LINE wherever this transpilation occurs.

This PR also drops support for $\z because \z is not supported by cuDf. Alternatively, we could transpile $\z to $(?![\r\n\u0085\u2028\u2029]). However, cuDf doesn't support negative look ahead.

This PR also drops support for regex patterns with end-of-line anchors $ and \Z when followed by any escape sequences like \W, \B,\b etc, as they produce different results on CPU and GPU.

[NVnavkumar]

Can we confirm some of the behavior described in compatibility.md and update accordingly?

[SurajAralihalli]

Can we confirm some of the behavior described in compatibility.md and update accordingly?

Thank you for pointing it, I found another issue that is resolved by this PR. I've updated the guide and tests to reflect this.
As part of the process we also reviewed the feasibility of solving #10641 and #10764 in this PR. Updated these issues with the status.

[SurajAralihalli]

Build

[SurajAralihalli]

Build

[NVnavkumar]

LGTM. pending pre-merge.