Implement proc-macro-api versioning
So as it stands, we can't really change the proc-macro-api protocol at all without breaking all proc-macro servers again. To somewhat alleviate this we can move the supported ABI mess over to the proc-macro-api now by supporting multiple versions there (versions defined by us at least, not by rustc). Since the proc-macro-api protocol has no versioning scheme at the moment though, the best we can do here is add a new request to query the version from a server. Due to how the server currently works though, if it encounters an unknown request it will exit, meaning we can check if it is a server without support by checking if it exited after our version check request, that way we can support the current circulating server as well.
We need this since our span type will change from `TokenId` to something else at some point, but for that to work we need to comply with that the server expects. So knowing the version the server is using we can decide whether to send our new span data, or the tokenid (assuming we keep that information with our span data as well, alternatively we send irrelevant tokenids). That way we can keep old servers working while the user installations slowly migrate to newer servers that support the new spandata.
Support generic function in `generate_function` assist
Part of #3639
This PR adds support for generic function generation in `generate_function` assist. Now the assist looks for generic parameters and trait bounds in scope, filters out irrelevant ones, and generates new function with them.
See `fn_generic_params()` for the outline of the procedure, and see comments on `filter_unnecessary_bounds()` for criteria for filtering. I think it's good criteria for most cases, but I'm open to opinions and suggestions.
The diff is pretty big, but it should run in linear time w.r.t. the number of nodes we operate on and should be fast enough.
Some notes:
- When we generate function in an existing impl, generic parameters may cause name conflict. While we can detect the conflict and rename conflicting params, I didn't find it worthwhile mainly because it's really easy to resolve on IDE: use Rename functionality.
- I've implemented graph structure myself, because we don't have graph library as a dependency and we only need the simplest one.
- Although `petgraph` is in our dependency graph and I was initially looking to use it, we don't actually depend on it AFAICT since it's only used in chalk's specialization graph handling, which we don't use. I'd be happy to replace my implementation with `petgraph` if it's okay to use it though.
- There are some caveats that I consider out of scope of this PR. See FIXME notes on added tests.
feat: Remove support for 1.58 proc-macro abi
This seems old enough that we can drop the support for it now, the less ABIs we have the less work it is adjusting our span implementation.
Extracted from https://github.com/rust-lang/rust-analyzer/pull/14061, will rebase that over this once merged.
