Implements MCP 577.

These are in places where a `tcx` is easily obtained.

There is a type `QueryCtxt`, which impls the trait `QueryContext`.
Confusingly, there is another type `QueryContext`. The latter is (like
`TyCtxt`) just a pointer to a `GlobalContext`. It's not used much, e.g.
its `impl` block has a single method.

This commit removes `QueryContext`, replacing its use with direct
`GlobalCtxt` use.

… r=wesleywiser

Support `true` and `false` as boolean flag params

Implements [MCP 577](rust-lang/compiler-team#577).

…li-obk

Query refactoring

Just some cleanups I found when learning about the query system.

Best reviewed one commit at a time.

r? `@oli-obk`

…anonur

Handled snap curl issue inside Rust

…laumeGomez

rustdoc: remove unused fn parameter `tab`

…mulacrum

Sync release notes for 1.67.1

Closes rust-lang#107859.

…e-candidates, r=jackh726

Allow multiple candidates with same response in new solver

Treat >1 candidates as *not* ambiguous if they return the same response.