[UIK-2230] Add BulkTextarea documentation

[j-mnizhek]

Motivation and Context

How has this been tested?

This PR add documentation for our new component #1893:

• New page with all the necessary sections: Design, A11y, API, Example, Changelog
• A svg illustration for Components showcase page

Documenatation needs to be updated according to the actual component.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).
• Nice improve.

Checklist:

• My code follows the code style of this project.
• I have updated the documentation accordingly or it's not required.
• Unit tests are not broken.
• I have added changelog note to corresponding CHANGELOG.md file with planned publish date.
• I have added new unit tests on added of fixed functionality.

[j-mnizhek]

Merged this branch into #1893

@sheila-semrush Sheila, can you please take a look at the BulkTextarea documentation. Maybe I've missed something or you will have something to suggest 😎

BTW, the following will be fixed in the #1893

(THESE NAMES ARE TEMPORARY, WILL BE UPDATED ACCORDING TO THE ACTUAL COMPONENT)

BulkTextarea.Label
BulkTextarea.Textarea
BulkTextarea.TextareaRows
BulkTextarea.TextareaRowsItem
BulkTextarea.Navigation
BulkTextarea.ClearButton