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_passes/src/lib.rs

@@ -26,6 +26,7 @@ use rustc_middle::ty::query::Providers;
 mod check_attr;
 mod check_const;
 pub mod dead;
+mod debugger_visualizer;
 mod diagnostic_items;
 pub mod entry;
 pub mod hir_id_validator;
@@ -47,6 +48,7 @@ pub fn provide(providers: &mut Providers) {
     check_attr::provide(providers);
     check_const::provide(providers);
     dead::provide(providers);
+    debugger_visualizer::provide(providers);
     diagnostic_items::provide(providers);
     entry::provide(providers);
     lang_items::provide(providers);