zlog: Use zlog as default log implementation (#28612)

Still TODO:

- [x] Remove old log implementations
- [x] More cleanup
- [x] Verify atomic/lock logic
- [x] More tests
- [ ] ??? Ansi coloring when logging to stdout

Release Notes:

- N/A

crates/zed/Cargo.toml

@@ -108,7 +108,6 @@ session.workspace = true
 settings.workspace = true
 settings_ui.workspace = true
 shellexpand.workspace = true
-simplelog.workspace = true
 smol.workspace = true
 snippet_provider.workspace = true
 snippets_ui.workspace = true