Support build_type parameter

[limitusus]

Describe the Feature

Specify ARM_CONTAINER for environment.type of aws_codebuild_project resource.
Of course CodeBuild is wrapped with cloudposse/terraform-aws-codebuild, and it accepts this value as build_type variable.

Expected Behavior

build_type parameter is supported that is to be passed to cloudposse/terraform-aws-codebuild module.
https://github.com/cloudposse/terraform-aws-codebuild/blob/master/main.tf#L343

Use Case

I want to run CodeBuild on Graviton2.

Describe Ideal Solution

Add a parameter.

Alternatives Considered

N/A

Additional Context

N/A