Closes #ISSUE

Creates a function named `normalized_ctx_eq` that compares
`gpui::KeybindContextPredicate`'s while taking into account the
associativity of the binary operators. This function is now used to
compare context predicates in the keymap editor, greatly improving the
number of cases caught by our overloading and conflict detection

Release Notes:

- N/A *or* Added/Fixed/Improved ...