aws_kms: handle updated policy format+cleanup (#30728)
aws_kms: handle updated policy format+cleanup (#30728)

* aws_kms: handle updated policy format+cleanup

- create slightly updated policy in that handles lists instead of a single string; the previous version's policy was being rejected if the key was new enough to have the updated base policy.
- removed `dry_run` conditionals, not committing the policy anyhow.
- return the policy in the return data. Leaving undocumented for now.
- update exception handling: don't rethrow in `do_grant`, don't pass anything to `format_exc`.

* whitespace/indent fail

* fix list-plus-brackets

* str and list fixes for ryansb

* port changes from #31667 over, better listification

thaim/ansible,thaim/ansible