[86bxzr7kb][data-table, scroll-area, spin-container, docs] handle case when data-table is used with fixed header and spin container

[msereniti]

Motivation and Context

We have bad handled edge case – when table contains fixed head and displays loading state with spin container.

To better handle it:

1. Added focus ring offset api to ScrollArea
2. On DataTable body focus ring top border moved for 3 pixels lower to prevent overlapping with fixed header.
3. On SpinContainer added feature to render it in advanced mode without SpinContainer.Content
4. Added new documentation example

How has this been tested?

Manually on added examples

Screenshots:

Types of changes

• [x] 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:

• [x] My code follows the code style of this project.
• [x] I have updated the documentation accordingly or it's not required.
• [x] Unit tests are not broken.
• [x] 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.