Add task docs and default keybindings (#8123)

Also group task source modules together

Release Notes:

- N/A

---------

Co-authored-by: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>

crates/tasks_ui/src/lib.rs

@@ -2,13 +2,11 @@ use std::path::PathBuf;
 
 use gpui::{AppContext, ViewContext, WindowContext};
 use modal::TasksModal;
-pub use oneshot_source::OneshotSource;
 use task::Task;
 use util::ResultExt;
 use workspace::Workspace;
 
 mod modal;
-mod oneshot_source;
 
 pub fn init(cx: &mut AppContext) {
     cx.observe_new_views(