Adding internal-billing-auditor admin role support

[haydengomes]

Description

A new internal-billing-auditor admin role was added to atlas

Testing plan

1. Updated helper_test.go to cover new role

External links

• Jira Ticket
• Related PR

Output from tests

Including output from tests may require access to a TFE instance. Ignore this section if you have no environment to test against.

$ TFE_ADDRESS="https://example" TFE_TOKEN="example" go test ./... -v -run TestFunctionsAffectedByChange

...
go test ./... -v -run TestFunctionsAffectedByChange
?   	github.com/hashicorp/go-tfe/examples/backing_data	[no test files]
?   	github.com/hashicorp/go-tfe/examples/configuration_versions	[no test files]
?   	github.com/hashicorp/go-tfe/examples/organizations	[no test files]
?   	github.com/hashicorp/go-tfe/examples/registry_modules	[no test files]
?   	github.com/hashicorp/go-tfe/examples/run_errors	[no test files]
?   	github.com/hashicorp/go-tfe/examples/state_versions	[no test files]
?   	github.com/hashicorp/go-tfe/examples/users	[no test files]
?   	github.com/hashicorp/go-tfe/examples/workspaces	[no test files]
?   	github.com/hashicorp/go-tfe/mocks	[no test files]
testing: warning: no tests to run
PASS
ok  	github.com/hashicorp/go-tfe	0.277s [no tests to run]

[hashicorp-cla]

All committers have signed the CLA.