fix: anchored-region locks to viewport allows anchor overlap

[scomea]

Pull Request

📖 Description

Modifies anchored-region viewport lock to work in both directions. Previously the region would not overlap the anchor to remain within the viewport, this change allows the region to move in either direction to remain in view. Note that regions that are bigger than the viewport still get clipped.

Applies "lock-to-viewport" to menu items.

🎫 Issues

closes https://github.com/microsoft/fast/issues/6125

✅ Checklist

General

• [x] I have included a change request file using $ yarn change
• [ ] I have added tests for my changes.
• [x] I have tested my changes.
• [ ] I have updated the project documentation to reflect my changes.
• [x] I have read the CONTRIBUTING documentation and followed the standards for this project.

Component-specific

• [ ] I have added a new component
• [x] I have modified an existing component
• [ ] I have updated the definition file
• [ ] I have updated the configuration file

[chrisdholt]

@scomea could we create a PR perhaps via cherry pick for these commits into archives/fast-element-1? Given #6186 I think this is most necessary to resolve existing bugs in the FE1 branch which still publishes to stable. Once that's up I think this can go right in.