[openimageio] add libheif as an optional dependency, remove libsquish as a dependency

[russelltg]

Workaound for #29156, but also is a good feature. Additionally, libsquish is not a dependency as of AcademySoftwareFoundation/OpenImageIO@5e67c09#diff-0d57038c2e7b5bf8660e3859a78c7e96fbdb6b77604d4510e137de90b9e8f9e7

• Changes comply with the maintainer guide
• 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.

[BillyONeal]

Thanks!