gh-86519: Add prefixmatch APIs to the re module (GH-31137)

Adds `prefixmatch` APIs to the re module as an alternate name for our long existing `match` APIs to help alleviate a common Python confusion for those coming from other languages regular expression libraries.

These alleviate common confusion around what "match" means as Python is different than other popular languages regex libraries in our use of the term as an API name.  The original `match` names are **NOT being deprecated**.  Source tooling like linters, IDEs, and LLMs could suggest using `prefixmatch` instead of match to improve code health and reduce cognitive burden of understanding the intent of code when configured for a modern minimum Python version.

See the documentation changes for a better description.

Discussions took place in the PR, in the issue, and finally at https://discuss.python.org/t/add-re-prefixmatch-deprecate-re-match/105927

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>