git: Implement a basic repository selector (#23419)

This PR adds a rough-and-ready picker for selecting which of the
project's repositories the git panel should display.

Release Notes:

- N/A

---------

Co-authored-by: Nate Butler <iamnbutler@gmail.com>
Co-authored-by: Nate <nate@zed.dev>

crates/util/Cargo.toml

@@ -32,7 +32,7 @@ rust-embed.workspace = true
 serde.workspace = true
 serde_json.workspace = true
 smol.workspace = true
-take-until = "0.2.0"
+take-until.workspace = true
 tempfile = { workspace = true, optional = true }
 unicase.workspace = true