computer: Add workspace tools changeset

Record the new search and deletion tools and shared mutation locking
with the Computer package that exposes them.

Author: aron-cf

.changeset/computer-workspace-file-tools.md

@@ -0,0 +1,5 @@
+---
+"@cloudflare/computer": minor
+---
+
+Add bounded `find` and `grep` tools, a read-only-aware `delete` tool, and shared locking for file mutations.