* [vcpkg registries] Add git registries support
* Add git registries support to the registries module of vcpkg.
* add e2e tests for git registries
* fix vcpkg.cmake for registries
* fix CRs, remove a thing
* better error messages
* Billy CRs
* fix Robert's CR comment
* I learned about `-c` today
* format
* fix baseline.json
* failing to find baseline is technically not a bug
* [vcpkg] Change version field in `baseline.json`
* Change name from `version-tag` to `baseline`
* [vcpkg] x-history serializes version scheme
* Update e2e tests
* Update baseline e2e test
* [vcpkg registries] support versions
This PR merges the Registries changes and the versioning changes, so that one can use both at the same time.
There is one major difference between this PR and the RFC (#13590), which is that instead of version files looking like:
```json
[
...
]
```
version files look like:
```
{
"versions": [
...
]
}
```
this is to support interop between this PR and existing demos and the like;
fixing this, along with perhaps renaming `port_versions` to `port-versions` should be done after this is merged,
should be a trivial change.
