Adds border to conversation actions

Fixes: CNVS-14504

Added a border on focus to read and starred actions
for conversation messages.

Test-Plan:
1.) Make sure the user you're logged in as has messages
2.) Navigate to inbox
3.) Tab navigate to the conversation actions
4.) Verify that they have borders
5.) Check the action boxes
6.) Verify that on focus they have borders that are visible

Change-Id: I79e42faf6e3951b09133662b3ee6748d077790a5
Reviewed-on: https://gerrit.instructure.com/40437
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Matthew Wheeler <mwheeler@instructure.com>
Product-Review: Dana Danger <dana@instructure.com>
QA-Review: Steven Shepherd <sshepherd@instructure.com>