feat: updated prevent typing over-long topic names

[ARYPROGRAMMER]

This PR helps in addition of the feature "prevention of typing over long topic names" and is referred from #1230 and fixes issue #1218.

Contains a cleaner PR.

• It implements a value notifier, adds a listener and creates a function to enforce limit.
• Displays the limit alongside current characters
• Does not change any core functionality and does not break anything else

Demo Video on a real android device:

demo.mp4

[chrisbobbe]

I see you've already opened a PR for this feature: #1230. Please update that PR with your latest revision: #1230 (comment)