LSIF/SCIP support

[withered-magic]

As suggested in https://github.com/cgrindel/starlark-language-server/pull/1#discussion_r1238228876

LSIF: https://microsoft.github.io/language-server-protocol/specifications/lsif/0.4.0/specification/ SCIP: https://github.com/sourcegraph/scip

[davo-canva]

Given starpls is heavily based on rust-analyzer, might be relatively easy to pull together the SCIP support from there.

• https://github.com/rust-lang/rust-analyzer/blob/b51f9bc736dc0472481a47d7c05de2901323e543/crates/rust-analyzer/src/cli/scip.rs
• https://github.com/rust-lang/rust-analyzer/blob/b51f9bc736dc0472481a47d7c05de2901323e543/crates/ide/src/static_index.rs#L28