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/worktree_store.rs

@@ -551,7 +551,7 @@ impl WorktreeStore {
             let worktree = cx.update(|cx| {
                 Worktree::remote(
                     REMOTE_SERVER_PROJECT_ID,
-                    0,
+                    ReplicaId::REMOTE_SERVER,
                     proto::WorktreeMetadata {
                         id: response.worktree_id,
                         root_name,