Auto merge of #111641 - michaelwoerister:debugger-visualizer-fixes, r=cjgillot

Fix dependency tracking for debugger visualizers

This PR fixes dependency tracking for debugger visualizer files by changing the `debugger_visualizers` query to an `eval_always` query that scans the AST while it is still available. This way the set of visualizer files is already available when dep-info is emitted. Since the query is turned into an `eval_always` query, dependency tracking will now reliably detect changes to the visualizer script files themselves.

TODO:
 - [x] perf.rlo
 - [x] Needs a bit more documentation in some places
 - [x] Needs regression test for the incr. comp. case

Fixes rust-lang/rust#111226
Fixes rust-lang/rust#111227
Fixes rust-lang/rust#111295

r? `@wesleywiser`
cc `@gibbyfree`

Author: bors