feature request: SOVERSION check in package_contents

[minrk]

I have a reason in a recipe to make sure the versioned library files are present as expected. (i.e. libfoo.dylib, libfoo.1.dylib, libfoo.1.2.3.dylib)

This can be done in a script, which isn't too bad, but it's a little tedious because the ordering of SHLIB_EXT and SOVERSION are different on linux/mac:

tests:
  - script:
      - if: osx
        - test -f $PREFIX/lib/libfoo.$(echo ${PKG_VERSION} | cut -d. -f1 )${SHLIB_EXT}
        - test -f $PREFIX/lib/libfoo.${PKG_VERSION}${SHLIB_EXT}
      - if: linux
        - test -f $PREFIX/lib/libfoo${SHLIB_EXT}.$(echo ${PKG_VERSION} | cut -d. -f1 )
        - test -f $PREFIX/lib/libfoo${SHLIB_EXT}.${PKG_VERSION}

but it would be awesome if package_contents.lib understood this, so I could have something like:

ouputs:
  - package:
      name: libsomething
      version: 1.2.3 # different from recipe version
    tests:
      - package_contents:
          lib:
          - name: foo
            so_version:
              # I don't actually know what variable is available for the output version; can outputs have their own `context`?
              - ${{ output_version }} # libfoo.1.2.3.dylib
              - ${{ output_version | major_version }} # libfoo.1.dylib

that does the right thing (including ignoring the version on Windows, I think). Double bonus points if I could also assert that install_name / soname points to a specific version (libfoo.X.dylib / libfoo.so.X) because it is a common mistake in libraries to do this wrong, and relevant to the validation of pinning in run_exports (e.g. if install_name is libfoo.1.2.3.dylib, run_exports pinning must set max_pin=x.x.x as max_pin='x' will result in broken packages with 'library not found' when 1.2.4 is released).