Add a registry for GitHostingProviders (#11470)

This PR adds a registry for `GitHostingProvider`s.

The intent here is to help decouple these provider-specific concerns
from the lower-level `git` crate.

Similar to languages, the Git hosting providers live in the new
`git_hosting_providers` crate.

This work also lays the foundation for if we wanted to allow defining a
`GitHostingProvider` from within an extension. This could be useful if
we wanted to extend the support to work with self-hosted Git providers
(like GitHub Enterprise).

I also took the opportunity to move some of the provider-specific code
out of the `util` crate, since it had leaked into there.

Release Notes:

- N/A

crates/fs/src/fs.rs

@@ -1,4 +1,5 @@
 use anyhow::{anyhow, Result};
+use git::GitHostingProviderRegistry;
 
 #[cfg(unix)]
 use std::os::unix::fs::MetadataExt;
@@ -117,12 +118,19 @@ pub struct Metadata {
 
 #[derive(Default)]
 pub struct RealFs {
+    git_hosting_provider_registry: Arc<GitHostingProviderRegistry>,
     git_binary_path: Option<PathBuf>,
 }
 
 impl RealFs {
-    pub fn new(git_binary_path: Option<PathBuf>) -> Self {
-        Self { git_binary_path }
+    pub fn new(
+        git_hosting_provider_registry: Arc<GitHostingProviderRegistry>,
+        git_binary_path: Option<PathBuf>,
+    ) -> Self {
+        Self {
+            git_hosting_provider_registry,
+            git_binary_path,
+        }
     }
 }
 
@@ -474,6 +482,7 @@ impl Fs for RealFs {
                 Arc::new(Mutex::new(RealGitRepository::new(
                     libgit_repository,
                     self.git_binary_path.clone(),
+                    self.git_hosting_provider_registry.clone(),
                 )))
             })
     }