chore: Extract PromptStore out of prompt_library (#25837)

One step closer to removing long pole with assistant/assistant2 builds

Release Notes:

- N/A

crates/collab/src/tests/integration_tests.rs

@@ -14,7 +14,7 @@ use client::{User, RECEIVE_TIMEOUT};
 use collections::{HashMap, HashSet};
 use fs::{FakeFs, Fs as _, RemoveOptions};
 use futures::{channel::mpsc, StreamExt as _};
-use prompt_library::PromptBuilder;
+use prompt_store::PromptBuilder;
 
 use git::status::{FileStatus, StatusCode, TrackedStatus, UnmergedStatus, UnmergedStatusCode};
 use gpui::{