clock: Cleanup ReplicaId, Lamport and Global (#40600)

- Notable change is the use of a newtype for `ReplicaId`
- Fixes `WorktreeStore::create_remote_worktree` creating a remote
worktree with the local replica id, though this is not currently used
- Fixes observing the `Agent` (that is following the agent) causing
global clocks to allocate 65535 elements
- Shrinks the size of `Global` a bit. In a local or non-collab remote
session it won't ever allocate still.

Release Notes:

- N/A *or* Added/Fixed/Improved ...

crates/project/src/project_tests.rs

@@ -4307,7 +4307,7 @@ async fn test_rescan_and_remote_updates(cx: &mut gpui::TestAppContext) {
     let remote = cx.update(|cx| {
         Worktree::remote(
             0,
-            1,
+            ReplicaId::REMOTE_SERVER,
             metadata,
             project.read(cx).client().into(),
             project.read(cx).path_style(cx),