[liblsquic] Add new port

[rpavlik]

Adds a port for lsquic, an implementation of several versions of QUIC and HTTP/3.

The thing I have the biggest question about is the submodules: I tried to follow the technique I saw in a few other ports, but not sure if it's the preferred way.

• Which triplets are supported/not supported? Have you updated the CI baseline?

I have tested Linux and Windows, have not updated the CI baseline.

• Does your PR follow the maintainer guide?

Yes - patches have already been upstreamed and dropped.

• If you have added/updated a port: Have you run ./vcpkg x-add-version --all and committed the result?

yes

[github-actions]

You have modified or added at least one vcpkg.json where a "license" field is missing.

If you feel able to do so, please consider adding a "license" field to the following files:

• ports/liblsquic/vcpkg.json

Valid values for the license field can be found in the documentation

[rpavlik]

You have modified or added at least one vcpkg.json where a "license" field is missing.

I can add this

[rpavlik]

OK, I have added the license field, removed the unneeded patch, and the install patch has been submitted upstream. Not sure if there's anything I need to do to explicit update the CI baseline, since it appears to build everywhere just fine.

[rpavlik]

Oh, hmm, I missed this detail in the maintainer guide at first: "Libraries that don't provide a .def file and do not use __declspec() declarations simply do not support shared builds for Windows and should be marked as such with vcpkg_check_linkage(ONLY_STATIC_LIBRARY)." I think it only provides a C api, do I still need to add this line? It's been apparently working OK with shared builds on Windows here...

[rpavlik]

OK I added vcpkg_check_linkage(ONLY_STATIC_LIBRARY) on Windows in the portfile.

[rpavlik]

OK, revised as requested.

[rpavlik]

OK, works on x64-windows, x64-windows-static, and x64-linux.

Had to put in a file install because it was yanked in a bulk release commit which I had missed. ( PR to restore upstream litespeedtech/lsquic#389 )

This is ready to review and merge. I'm following up on the 32-bit stuff (and the one required cast litespeedtech/lsquic#388 ) and the PERL/PERL_EXECUTABLE (litespeedtech/lsquic#387 litespeedtech/ls-qpack#42 )

[JackBoosY]

Testing this port locally.

[JackBoosY]

Already tested successfully on x64-windows, x64-windows-static, x64-linux.