[Tagging] Bulk delete of multiple tags from Taxonomy Detail Page

[bradenmacdonald]

"As an instance-level admin, I want to be able to select multiple tags for deletion and delete them all at once"

Acceptance Criteria

TBD: some details of the UX are being decided. See Figma.

1. Once checkboxes are shown, users can select or de-select tags. The count is updated to show how many are selected.
   
2. As long as at least one tag is selected, the "Delete tags" menu item appears.
3. Confirmation dialog is shown:
   
4. "the count of selected tags in the previous screen was 498 and the number shown here is only 496. This is because 2 of the selected tags ("Career and Technical Education" and "Agriculture") are parents of a remaining child tag ("Horticulture and Landscaping") and thus cannot be deleted."
5. A toast is shown stating how many tags were deleted.
   

[ali-hugo]

@bradenmacdonald The UX for this has been finalized. Please see the user flow outlined here.

Let me know if there's anything you need in order to remove the "pending UX changes" label from this issue.