[librsvg][gdk-pixbuf] Add librsvg support to gdk-pixbuf by adding librsvg as a dependency to gdk-pixbuf.

[AenBleidd]

This changes the behavior of librsvg to be able to be built without gdk-pixbuf support (to avoid circular dependency) when built statically, and gdk-pixbuf to be built with librsvg support. librsvg is optional when building gdk-pixbuf dynamically, and enabled by default when building statically.

This fixes #38012.

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