actionbar: move BarAction and add execute method

We will be executing baractions in multiple places, so factor this
out.

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

src/lib.rs

@@ -5,6 +5,7 @@ mod error;
 //mod block;
 mod abbrev;
 pub mod account_manager;
+mod actionbar;
 pub mod app_creation;
 mod app_style;
 mod colors;