Fix keybindings list being empty by default (#13456)

# Description

Made a mistake when fixing this for IR. The default behavior with no
options set is to list everything. Restored that.

This should go in the 0.96.1 patch release.

# Tests + Formatting
Added regression test.

crates/nu-cli/tests/commands/mod.rs

@@ -1 +1,2 @@
+mod keybindings_list;
 mod nu_highlight;