Feature/externalID

[aq17]

• Require valid externalID to impersonate service account
• Fix errors in creating benchmark task/ cloud account

[aq17]

This PR includes/ fixes the single benchmark task changes from this PR also #37

[wideawakening]

@aq17 we gave a look at this

• pushed pre-merge check issue fixes, that are mandatory before merge
• most of these checks can be pre-validated using the pre-commit plugin, which is explained in the /CONTRIBUTE.md (just uploaded it, is same for every terraform module we have for the moment).
• as long as checks are OK you're good to merge

now, besides these modifications, integration tests fail on

• single; seems like there's a conflict in the sysdig_secure_cloud_account (may be one of benchmark collides on subsequent/concurrent testing #44 ?)
  error ➡️ https://github.com/sysdiglabs/terraform-google-secure-for-cloud/pull/55/checks?check_run_id=3826098145#step:5:873
• organizational; error ➡️ https://github.com/sysdiglabs/terraform-google-secure-for-cloud/pull/55/checks?check_run_id=3826098145#step:5:1033

[wideawakening]

merged in #55