Add a config option to specify that certain URIs are forced to be "anarchist" URIs

We are currently using nsIPrincipal in Gecko to get the origin and base domain information from an URI, but that can only be called on the main thread and we would like to call it directly on a background thread. MozURL which is backed by rust-url can be used on any thread, but it lacks support for some mozilla specific URIs (like moz-extension://foo/bar, resource://foo/bar, about:home, indexeddb://fx-devtools, etc.). Most of those can be handled in MozURL implementation. However there's one thing that has to be checked directly in rust-url parser.

I'm attaching a patch that demonstrates the issue:

bug_1526891_part_1_add_support_for_simple_uris_to_rust_url_r_nika.txt

Basically, those URIs shouldn't have an authority, so some form of configuration to specify that these URIs are forced to be "anarchist" URIs is required.

What would be the best way to support that ?

Read the attached bug_1526891_part_1_add_support_to_simple_uris_to_rust_url_r_nika.txt patch and the rust-url parser paths involved in authority handling. Define how configuration for forced “anarchist” URIs should be exposed and verify that the listed Mozilla-specific URI forms parse without an authority while existing URI behavior remains unchanged.