change versioning scheme of clippy_lints

As mentioned in https://github.com/rust-lang/rust/pull/50767, updating the clippy submodule in the rustc repo can break rls and thus break nightlies.

Yesssss!, we can now ensure that all nightlies have a working clippy if we want to

No we are of course not doing this :P

Anyway. My suggestion is to change the versioning scheme of the clippy_lints crate. Instead of syncing with the clippy crate, we start producing 0.x.y versions, where x is updated when we change the API of clippy_lints (so when rustc forces us to change the API) and y is updated whenever we do a rustup.

This means there'll be a lot fewer version bumps to the clippy crate, as the clippy_lints crate in the background would automatically update via patch versions.

Is this suggestion abusing semver? Other ideas?

Start by reading the linked rust-lang/rust pull request and tracing how the clippy and clippy_lints crate versions are currently synchronized. Check the impact on rustc, rls, and nightly rustup updates. Done means there is an agreed versioning approach that avoids breaking RLS or nightlies and is documented well enough to implement.