Add trigger token for executor usage

[daved]

DX-1588 Separate trigger for `state exec` and executors

[daved]

@Naatan In the AC, the state exec command is to get a new token as "exec-cmd". However this would then not match with other commands like activate which do not use that suffix. I added a new token for executors simply named "executor". I'm happy to redo the changes to match AC more exactly if the odd "-cmd" suffix is desirable, or, alternatively, the new "executor" token can be renamed to be more distinct from the existing "exec" token.

[Naatan]

Please stick to the original AC's. I agree the naming inconsistency is awkward, but ultimately inconsequential and it's better than having DW have to handle runtime tracking using a different trigger for some version or date cutoff.

I'm always happy to chat on Slack if AC's are posing problems. Rather we have a quick chat and adjust the AC's before investing time on implementation.