fix: allow members with git providers permission to create and delete their own (#4713)

The canAccessToGitProviders legacy override only granted read access, so
members with the Git Providers toggle enabled could not add providers — the
create/delete endpoints require gitProviders.create / gitProviders.delete.
This mirrors how the SSH Keys toggle already grants read/create/delete.

The git-provider remove endpoint now restricts non owner/admin roles to
deleting only their own providers (matching the ownership model used for
visibility and sharing), while owner/admin can still delete any provider in
the organization.

Closes #4695

packages/server/src/services/permission.ts

@@ -170,6 +170,8 @@ const getLegacyOverrides = (
 		},
 		gitProviders: {
 			read: !!memberRecord.canAccessToGitProviders,
+			create: !!memberRecord.canAccessToGitProviders,
+			delete: !!memberRecord.canAccessToGitProviders,
 		},
 	};
 };