Refactor input listener for inline

[dingfeli]

Premise

The existing typeahead logic leverages a single verifyKey listener to verify all user input keystrokes.
This makes it the logic very convoluted and hard to deal with edge cases.
A refactor to separate the listener into verifyKey + verifyText would help clean up the / simplify the logic.

Description of changes:
With this change, the following bugs were fixed:

• Fix vertical indent not being on the right line when there are auto closing curly braces
• Fix caret movement check becoming overly loose or stringent
• Fix backspacing on typed brackets causing input listener to crash

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