Add support for a new attribute #[debugger_visualizer] to support embedding debugger visualizers into a generated PDB.

Cleanup `DebuggerVisualizerFile` type and other minor cleanup of queries.

Merge the queries for debugger visualizers into a single query.

Revert move of `resolve_path` to `rustc_builtin_macros`. Update dependencies in Cargo.toml for `rustc_passes`.

Respond to PR comments. Load visualizer files into opaque bytes `Vec<u8>`. Debugger visualizers for dynamically linked crates should not be embedded in the current crate.

Update the unstable book with the new feature. Add the tracking issue for the debugger_visualizer feature.

Respond to PR comments and minor cleanups.

compiler/rustc_middle/src/query/mod.rs

@@ -1628,6 +1628,12 @@ rustc_queries! {
         desc { "looking at the source for a crate" }
         separate_provide_extern
     }
+    /// Returns the debugger visualizers defined for this crate.
+    query debugger_visualizers(_: CrateNum) -> Vec<rustc_span::DebuggerVisualizerFile> {
+        storage(ArenaCacheSelector<'tcx>)
+        desc { "looking up the debugger visualizers for this crate" }
+        separate_provide_extern
+    }
     query postorder_cnums(_: ()) -> &'tcx [CrateNum] {
         eval_always
         desc { "generating a postorder list of CrateNums" }