RFR: 7903357: add a jextract sample that uses pcre2 library

[Athijegannathan Sundararajan]

Simple sample that checks a given string for matches against the given regex

-------------

Commit messages:
 - 7903357: add a jextract sample that uses pcre2 library

Changes: https://git.openjdk.org/jextract/pull/88/files
 Webrev: https://webrevs.openjdk.org/?repo=jextract&pr=88&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903357
  Stats: 125 lines in 8 files changed: 119 ins; 4 del; 2 mod
  Patch: https://git.openjdk.org/jextract/pull/88.diff
  Fetch: git fetch https://git.openjdk.org/jextract pull/88/head:pull/88

PR: https://git.openjdk.org/jextract/pull/88