Update/Add logging to Block

[eviljeff]

follow-on from #7225

When a Block is created the sign-off user should be noted in the logs

[AlexandraMoga]

@eviljeff I can see the following logs when I'm looking in the Activity log and in a Block submission History:

Activity Log (sign-off for a new add-on added to blocks and a block edit)

Block submission history (with sign-off)

Also, you might want to loo at #7322 as a potential regression.