Rework of the character count requirements display

[Oaphi]

This PR reworks the display of character count requirements, including:

• adds a shared char_count view for reusable & configurable character counters;
• adds proper abstractions (setCounterState, setInputState, setSubmitButtonState) for the character_count JS handler;
• ensures character count limits are always displayed on initial load so as the user knows how many they can enter (or left to enter);
• ensures current character count is properly displayed in forms with content already set;

The following is an example of how the character count will work after the change:

Screencast.from.23.08.2023.17.19.13.webm

Closes #1145