Add PCRE2 support

[wader]

This is still work in progress.

Work on oniguruma (https://github.com/kkos/oniguruma) has been discontinued
so we need to find some other regex implementation.

To build and test:
./configure --with-oniguruma=no --with-pcre2
make
make check
./jq --run-tests < ./tests/onig.test
./jq --run-tests < ./tests/pcre2.test

Known TODOs:

• Proper configure options (skip vendor for pcre2?)
  • Support both for a while?
• libjq usage? dont builtin and require libpcre2? (seems to be what debian does)
• pcre2 in ci/release workflows
  • Drop some archs and use docker to simplify things?
  • For macos use native builder instead of cross compile?
• Update Dockerfile
• Update docs
  • Breaking changes
    • Drop "l" modifier?
      • Could possibly reimplement
    • Empty pattern and multi-byte code points behave differntly. I think pcre2 is more correct?
      • onig: jq -n '["🚀" | match(""; "g")] | length' -> 5 (per byte it seems)
      • pcre2: jq -n '["🚀" | match(""; "g")] | length' -> 2 (per code point)

Good references:

• https://github.com/PCRE2Project/pcre2/blob/master/src/pcre2demo.c
  Pre pcre2_next_match usage:
• https://github.com/PCRE2Project/pcre2/blob/eb3bd3cf1418cb1a0eabf984b0b1e80b6bdd9314~1/src/pcre2demo.c (pre pcre2_next_match usage)
• pcre2test cli tools is a good Playaround for pcre2

Notes:
".+?\b" test in onig.test seems to be behaves differently depending on pcre2 version.
I suspect this fix in 10.43:
PCRE2Project/pcre2@0a55280

I noticed a clang -fsanitize=memory use-of-uninitialized-valu issue but it seems to go awa with pcre2 master

Related to #3313

[wader]

Looking at the download stats maybe it would be ok to skip some arch? and then we could probably also gets away with using docker for cross builds.

$ curl -s https://api.github.com/repos/jqlang/jq/releases | jq -c '.[] | select(.tag_name == "jq-1.8.1").assets | map({name,download_count}) | sort_by(-.download_count)[]'
{"name":"jq-linux64","download_count":1557635}
{"name":"jq-linux-amd64","download_count":1175823}
{"name":"jq-windows-amd64.exe","download_count":264340}
{"name":"jq-osx-amd64","download_count":250878}
{"name":"jq-macos-amd64","download_count":218746}
{"name":"sha256sum.txt","download_count":208786}
{"name":"jq-macos-arm64","download_count":150022}
{"name":"jq-1.8.1.tar.gz","download_count":97404}
{"name":"jq-linux-arm64","download_count":88325}
{"name":"jq-win64.exe","download_count":73076}
{"name":"jq-windows-i386.exe","download_count":8321}
{"name":"jq-1.8.1.zip","download_count":3963}
{"name":"jq-linux-i386","download_count":2137}
{"name":"jq-linux-ppc64el","download_count":1778}
{"name":"jq-linux-s390x","download_count":1451}
{"name":"jq-linux-armhf","download_count":294}
{"name":"jq-linux-armel","download_count":194}
{"name":"jq-linux-mips64","download_count":156}
{"name":"jq-linux-mips","download_count":146}
{"name":"jq-linux-mips64el","download_count":140}
{"name":"jq-linux-riscv64","download_count":128}
{"name":"jq-linux-mips64r6el","download_count":110}
{"name":"jq-linux-mipsel","download_count":109}
{"name":"jq-linux-powerpc","download_count":109}
{"name":"jq-linux-mipsr6","download_count":105}
{"name":"jq-linux-mipsr6el","download_count":105}
{"name":"jq-linux-mips64r6","download_count":100}

skip armhf and below possibly?

[wader]

why this got complicated with pcre2 is that we're not vendoring it (i assume we don't want?) so to cross build like before we would have to cross build some version of pcre2 here. the new alternative is that we use docker build with emulation using the our Dockerfile which will end up using pcre2 from debian, that in turn would limit us in archs that can use this approach https://hub.docker.com/_/debian/tags?name=13-slim but maybe it's ok to limit us to whatever debian supports?