[feat] Should support `quickfix` adding missing feature

Problem

Currently, fix missing feature does not support quick fix.

failed to resolve: could not find `X` in `Y` the item is gated behind the `Z` feature

error[E0433]: failed to resolve: could not find `X` in `Y`
...
note: found an item that was configured out
    = note: the item is gated behind the `Z` feature

No quick fixes available

Currently

Need 5 human steps to fix

1. Click for full compiler diagnostic

2. Copy feature name Z, remember depedency name Y

3. Find Cargo.toml

4. Open Cargo.toml, locate Cargo.toml dependencies field Y

5. Alter Y = "1.2.3" to Y = { version = "1.2.3", features = ["Z"] }

Feat

Should support quickfix adding missing feature

Start by tracing rust-analyzer's handling of the shown compiler diagnostic and its quick-fix generation; the issue identifies Cargo.toml and the dependency feature syntax as the target configuration. The work is done when a diagnostic identifying dependency Y and feature Z offers a quick fix that adds Z to Y's dependency declaration.