CI tooling to ensure documentation and acceptance tests use Terraform 0.12 syntax

[gdavison]

Add CI tooling to ensure that all new documentation and acceptance test contributions use Terraform 0.12 syntax.

Was originally part of #8950.

[anGie44]

Data Source Testing Configurations Complete:

• A-E(bs Volumes) Fix config formatting for data sources (up to EBS volumes) #14395
• E(c2) - E(fs Mount) Fix config for data source tests #14399
• E(ip) - I(am Server) Fix config for data source tests #14400
• I(am User) - K(ms Key) Fix config for data source tests #14401
• L(ambda Alias) - M(sk Configuration) Fix config for data sources tests #14402
• Nat Gateway) - R(egions) Fix data source config formatting, 0.12 up to regions #14479
• R(oute53) - S(3 Bucket) Fix data source test configs (up to s3 bucket) #14483
• S(ecretsManager Secret Rotation) - V(pc Endpoint Service) Fix acc test configs (up to VPC endpoint) #14484
• V(pc Endpoint) - W(orkspaces Directory) Fix acc test configs (up to workspaces) #14485