feat(model manager): 💄 refactor model manager bulk actions UI

[joshistoast]

Summary

Redesigns the Model Manager's bulk actions UI for a more seamless and smooth integration.

Related Issues / Discussions

QA Instructions

Merge Plan

Checklist

• The PR has a short but descriptive title, suitable for a changelog
• Tests added / updated (if applicable)
• ❗Changes to a redux slice have a corresponding migration
• Documentation added / updated (if applicable)
• Updated What's New copy (if doing a release after this PR)

[lstein]

Tested and works very well.

However, there is a minor aesthestic issue that needs to be fixed. In the current main branch, the model type headings (e.g. "Main") have a higher z-level than the model names and thumbnails as shown here:

In the PR, the positions are reversed, so that the model names and thumbnails obscure the model type headings:

[lstein]

I just noticed an additional issue. The translation string for ModelManager.selectAll seems to be missing.

[joshistoast]

@lstein Fixed the overlapping issue, however the modelManager.selectAll is a translation I actually added to this PR because it was missing in the original implementation as demonstrable by your earlier screenshots.

[lstein]

Tested and working as advertised.