Feature: Enable JSON parsing for getting TF config variables

[relusc]

Fixes #954

This change enables the parsing of tfvars.json files for getting variables of the submitted TF config files. Uses the JSON parsing functionality provided by the package already used for HCL parsing.

[brikis98]

LGTM, thank you! I'll kick off tests now.

[relusc]

@brikis98 thanks for your review ! it seems like the tests failed, however those seem to be unrelated to my changes. Is there anything i can do or something that needs to be adjusted ?

[brikis98]

There's one test failure and it seems unrelated; some intermittent thing that we may have already fixed in master. Merging now, thanks!

[bj-1795]

@brikis98 Could you please help me understand how can we pass tfvars.json in terraform options??

[relusc]

@bj-1795 just use

terraformOptions := terraform.WithDefaultRetryableErrors(t, &terraform.Options{
	TerraformDir: "<path-to-terraform-dir>",
	VarFiles:     []string{"test.tfvars.json"},
})

so you basically just use the already known VarFiles