Revert "Revert "Revert "Revert "don't filter on `codeSnippet` but only on `label` and `filterText`, fixes #6320""""

This reverts commit 0c5f6e88.

fixes #9550

honor order when merging contributed menu items with legacy items, legacy items have order zero, #9153

related to #9686

fixes #9670

new action 'Show Snippets' which opens quick pick with a list of snippets for the current mode

fixes #9678

fixes #9666

Fixes #6731

When ctrl+m is pressed (only use default keybinding for now), tab will not be
passed to the pty and instead will propogate up and shift focus.

Part of #6731

fixes #8980

fixes #9099