Mattermost-server: WebApp: Provide the user feedback when creating a custom 'Category Name' that exceeds the character limit

[mattermod]

With the experimental sidebar enabled (System Console > Experimental > Features > Experimental Sidebar Features), the user has an option to create custom sidebar categories. There is a limit to the number of characters in the category name, and it would be nice to have better feedback that there's a character limit on the Category Name.

Current
We stop the user from adding more the 22 characters which feels odd, jarring, and confusing.

Proposed
Add a red border and negative character count to the end of the textbox based on the number of characters the user has exceeded. See the screenshot below for how this should work. If possible, the component added for this should be made reusable so that it can be used elsewhere in the app.

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JIRA: https://mattermost.atlassian.net/browse/MM-24635

[prazolpp]

I'd be happy to take this one on!

[prazolpp]

I have asked a question in the mattermost channel regarding this issue ... please check it out if you get a chance https://community.mattermost.com/core/pl/j7icqw6db7r1mmrth6bdghqhwe

[amyblais]

@esethna The Jira ticket was closed https://mattermost.atlassian.net/browse/MM-24635. Should this issue be closed too?

[esethna]

@amyblais sorry, mistake on my part closing the ticket, I reopened

[koox00]

I see it's _Up For Grabs_ so, I'd like to take this on