Allow all file types in `terraform check` goal

[frekw]

Describe the bug
Currently, the terraform backend only supports *.tf files. There are a lot of situations where other file types are necessary, such as when keeping configuration for some system in a .json or some other format, which is then read by the Terraform module.

I think it would be good to relax this constraint to support any and all filetypes, but keep the default to *.tf as to not have undesired consequences.

Pants version
2.21.0.rc0

OS
Linux

Additional info
n/a

[lilatomic]

You can use a files or resources target for those types of files, and add that target as a dependency of the terraform_module. Something like:

resources(name="certs", sources=["*.cer", "*.crt"])
terraform_module(dependencies=[":certs"])

This is similar to other backends work, where the SourcesField subclass will pull in only the files that are in that language, and other files are pulled in with resources or files