Upgrades for tf 0.15.x syntax changes

[woodcockr]

• deployment label module updated.
• syntax fixes for WAF (via module version update and related PR)
• provider alias syntax change for cloudfront aws us-east-1 provider.

Any PRs will require running terraform fmt -recursive successfully first. Please install terraform version v0.15.x on your local setup for this activity.

Why this change is needed

TF 0.15.x fully deprecates some older features - notably list() - and uses a different syntax for provider aliases (no more empty provider blocks).

Negative effects of this change

Will making this change break or change an existing functionality? flag it here THERE SHOULD BE NO CHANGED TO INFRASTRUCTURE FROM THESE CHANGES

[woodcockr]

Minor update to move the WAF module branch to master since it's related PR is now merged. All good to do.