S3: delete multiple files / objects / folders

## Problem

Deleting multiple S3 files/folders in AWS Explorer requires tedious steps for each item:

1. right-click, choose Delete
2. confirm prompt

Related: aws/aws-toolkit-jetbrains/issues/2563

## Expected behavior

This behavior outline should be common for all "batch" operations in the Toolkit:

- Customer can select multiple files and folders in the S3 browser, then delete in one action.
- If any operations fail, continue (unless the failures continue for some time).
- When the batch is done, show a message saying how many operations succeeded, and link to a log file or some other list showing which operations failed.
- Bonus: in AWS Explorer, can we highlight the items that failed to delete?

Start with the S3 browser's existing delete action and compare it with the batch-operation behavior described in the issue. Done means multiple selected files and folders can be deleted in one action, failures do not unnecessarily stop the batch, and the result reports successes while linking to failed operations.

Written by the indexing model from the issue text.