Rollup merge of #66297 - vakaras:edit-queries, r=oli-obk

Add a callback that allows compiler consumers to override queries.

This pull request adds an additional callback that allows compiler consumers such as Prusti and MIRAI to override queries. My hope is that in this way it will be possible to get access to the internal compiler information (e.g. borrow checker) without major changes to the compiler.

This pull request is work in progress because I am still testing if I can get the information which I need.

cc @nikomatsakis

r? @oli-obk

src/librustdoc/test.rs

@@ -79,6 +79,7 @@ pub fn run(options: Options) -> i32 {
         crate_name: options.crate_name.clone(),
         lint_caps: Default::default(),
         register_lints: None,
+        override_queries: None,
     };
 
     let mut test_args = options.test_args.clone();