* Migrate protobuf generation to Buf
Buf simplifies the generation story and allows us to lean
into other features in the Buf ecosystem, such as dependency
management, linting, breaking change detection, formatting
and remote plugins.
* Format all protobuf files with buf
Also add a CI job to ensure formatting remains consistent
* Add CI job to warn on proto generate diffs
Some files were not regenerated with the latest version
of the protobuf binary. This CI job will ensure we are always
detect if the protobuf files need regenerating.
* Add CI job for linting protobuf files
Add plugin version to GRPC interface
Added a version interface in the sdk/logical so that it can be shared between all plugin types, and then wired it up to RunningVersion in the mounts, auth list, and database systems.
I've tested that this works with auth, database, and secrets plugin types, with the following logic to populate RunningVersion:
If a plugin has a PluginVersion() method implemented, then that is used
If not, and the plugin is built into the Vault binary, then the go.mod version is used
Otherwise, the it will be the empty string.
My apologies for the length of this PR.
* Placeholder backend should be external
We use a placeholder backend (previously a framework.Backend) before a
GRPC plugin is lazy-loaded. This makes us later think the plugin is a
builtin plugin.
So we added a `placeholderBackend` type that overrides the
`IsExternal()` method so that later we know that the plugin is external,
and don't give it a default builtin version.
