[libssh2,libgit2,vcpkg-ci-libgit2] Fix, test, cleanup

[dg0yt]

libssh2

Fixes pc file for windows.
Enable building windows without openssl.

libgit2

Generally leverages pkg-config for dependencies:
Fixes #32433 (ssh) by using libssh2 pc files.
Fixes pcre2 debug lib name mismatch.

Rectifies exported unofficial cmake config:
Provide canonical unofficial-<port> package/unofficial::<port>::libgit2 target.
Drops pointless find_dependency.
Adds include dir property.

Adds usage hint, for pkg-config and cmake.

Fixes android builds (libgit2/libgit2#6574).

Add tools feature.

Fix mingw.

Revise copyright notice.

vcpkg-ci-libgit2

New test port, activates ssh and tools features.

• Changes comply with the maintainer guide
• SHA512s are updated for each updated download
• The "supports" clause reflects platforms that may be fixed by this new version
• Any fixed CI baseline entries are removed from that file.
• Any patches that are no longer applied are deleted from the port's directory.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Only one version is added to each modified port's versions file.

[LilyWangLL]

All features of libssh2 and feature libgit2[tools] passed on the following triplets:

x86-windows
x64-windows
x64-windows-static

Usage of libssh2 passed on x64-windows.
Usage of libgit2 passed on x64-windows.

[LilyWangLL]

Note: I will be converting your PR to draft status. When you respond, please revert to "ready for review". That way, I can be aware that you've responded since you can't modify the tags.

[BillyONeal]

Thanks!