Add support for self-hosted GitLab instances for Git permalinks (#19909)

This PR adds support for self-hosted GitLab instances when generating
Git permalinks.

If the `origin` Git remote contains `gitlab` in the URL hostname we will
then attempt to register it as a self-hosted GitLab instance.

A note on this: I don't think relying on specific keywords is going to
be a suitable long-term solution to detection. In reality the
self-hosted instance could be hosted anywhere (e.g.,
`vcs.my-company.com`), so we will ultimately need a way to have the user
indicate which Git provider they are using (perhaps via a setting).

Closes https://github.com/zed-industries/zed/issues/18012.

Release Notes:

- Added support for self-hosted GitLab instances when generating Git
permalinks.
- The instance URL must have `gitlab` somewhere in the host in order to
be recognized.

crates/git_hosting_providers/src/git_hosting_providers.rs

@@ -2,6 +2,7 @@ mod providers;
 
 use std::sync::Arc;
 
+use git::repository::GitRepository;
 use git::GitHostingProviderRegistry;
 use gpui::AppContext;
 
@@ -10,17 +11,27 @@ pub use crate::providers::*;
 /// Initializes the Git hosting providers.
 pub fn init(cx: &AppContext) {
     let provider_registry = GitHostingProviderRegistry::global(cx);
-
-    // The providers are stored in a `BTreeMap`, so insertion order matters.
-    // GitHub comes first.
-    provider_registry.register_hosting_provider(Arc::new(Github));
-
-    // Then GitLab.
-    provider_registry.register_hosting_provider(Arc::new(Gitlab));
-
-    // Then the other providers, in the order they were added.
-    provider_registry.register_hosting_provider(Arc::new(Gitee));
     provider_registry.register_hosting_provider(Arc::new(Bitbucket));
-    provider_registry.register_hosting_provider(Arc::new(Sourcehut));
     provider_registry.register_hosting_provider(Arc::new(Codeberg));
+    provider_registry.register_hosting_provider(Arc::new(Gitee));
+    provider_registry.register_hosting_provider(Arc::new(Github));
+    provider_registry.register_hosting_provider(Arc::new(Gitlab::new()));
+    provider_registry.register_hosting_provider(Arc::new(Sourcehut));
+}
+
+/// Registers additional Git hosting providers.
+///
+/// These require information from the Git repository to construct, so their
+/// registration is deferred until we have a Git repository initialized.
+pub fn register_additional_providers(
+    provider_registry: Arc<GitHostingProviderRegistry>,
+    repository: Arc<dyn GitRepository>,
+) {
+    let Some(origin_url) = repository.remote_url("origin") else {
+        return;
+    };
+
+    if let Ok(gitlab_self_hosted) = Gitlab::from_remote_url(&origin_url) {
+        provider_registry.register_hosting_provider(Arc::new(gitlab_self_hosted));
+    }
 }