Fixes#37974
png, jpeg and tiff support are [optional in
gdk-pixbuf](0edaedc560/meson_options.txt (L5)),
however [vcpkg has them
hard-wired](c5da4bafbd/ports/gdk-pixbuf/portfile.cmake (L37)).
Turn `png`,` jpeg` and `tiff` into features, and enable those 3 by
default to preserve compatibility.
- [x] Changes comply with the [maintainer
guide](https://github.com/microsoft/vcpkg-docs/blob/main/vcpkg/contributing/maintainer-guide.md).
- [ ] ~~SHA512s are updated for each updated download.~~
- [ ] ~~The "supports" clause reflects platforms that may be fixed by
this new version.~~
- [ ] ~~Any fixed [CI
baseline](https://github.com/microsoft/vcpkg/blob/master/scripts/ci.baseline.txt)
entries are removed from that file.~~
- [ ] ~~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.
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Co-authored-by: Jon <v-zhli17@microsoft.com>
dda6ab70d6