Switch to unified timeline cache via TimelineKinds

This is a fairly large rewrite which unifies our threads, timelines and
profiles. Now all timelines have a MultiSubscriber, and can be added
and removed to columns just like Threads and Profiles.

Signed-off-by: William Casarin <jb55@jb55.com>

crates/tokenator/Cargo.toml

@@ -5,3 +5,4 @@ edition = "2021"
 description = "A simple library for parsing a serializing string tokens"
 
 [dependencies]
+hex = { workspace = true }