[cmv4] Fix code hint unit tests

This is for #6042 and unit tests for url hints and js parameter code hints.

Changes:
* `token.className` has been replaced with `token.type`.
* CodeMirror "onKeyEvent" is no longer supported.

This fixes unit tests and I did some basic testing of code hints, but this has not been stress tested.

Note: use [?w=1](https://github.com/adobe/brackets/pull/6779/files?w=1) for Editor.js changes
cc @njx