Making supply of Keys optional by making locking optional

[motatoes]

Currently the requirement to support cloud account keys (AWS, GCP, Azure) is due to the fact that we need them to provision and use resources for locking. This adds extra cumbersome steps of getting keys and supplying them after forking the demo repository. Furthermore, after the initial fork the action runs and fails which gives impression that user did something wrong.

Proposal is to make locking optional and since the demo repo uses null resources it won't really be needed, instead we will demonstrate the digger in the most basic from allows you to collaborate on pull requests through several flows such as comment-based flow and see plans or applies directly in the pull request.

In case a user does not supply keys we proceed to perform the terraform action as usual but display a warning to the user saying that locking isn't being actioned since no keys were supplied and that they need to supply cloud account keys in order to allow locking.