Support for re-running failed tests

[bflad]

Certain tests may be flaky and it would be desirable to just re-run the failed tests instead of everything again. For example, this workflow is required now where the re-run command is copy-pasting elements from the results:

$ tctest pr 12530
Discovering tests for pr #12530 (https://github.com/terraform-providers/terraform-provider-aws/pull/12530)...
    TestAccAWSStorageGatewayNfsFileShare
triggering refs/pull/12530/merge for (TestAccAWSStorageGatewayNfsFileShare)...
  bflad@HOSTNAME#Aws_ProviderAwsAlternate
  build 103995 queued: https://HOSTNAME/viewQueued.html?itemId=103995

$ tctest results 103995
--- PASS: TestAccAWSStorageGatewayNfsFileShare_basic (198.28s)
--- PASS: TestAccAWSStorageGatewayNfsFileShare_ClientList (265.22s)
--- PASS: TestAccAWSStorageGatewayNfsFileShare_DefaultStorageClass (270.50s)
--- PASS: TestAccAWSStorageGatewayNfsFileShare_GuessMIMETypeEnabled (287.48s)
--- PASS: TestAccAWSStorageGatewayNfsFileShare_KMSKeyArn (303.82s)
--- PASS: TestAccAWSStorageGatewayNfsFileShare_tags (315.32s)
--- PASS: TestAccAWSStorageGatewayNfsFileShare_Squash (317.48s)
--- FAIL: TestAccAWSStorageGatewayNfsFileShare_KMSEncrypted (716.07s)
--- FAIL: TestAccAWSStorageGatewayNfsFileShare_NFSFileShareDefaults (768.03s)
--- FAIL: TestAccAWSStorageGatewayNfsFileShare_ObjectACL (775.86s)
--- FAIL: TestAccAWSStorageGatewayNfsFileShare_ReadOnly (775.84s)
--- FAIL: TestAccAWSStorageGatewayNfsFileShare_RequesterPays (791.91s)

$ tctest pr 12530 '(TestAccAWSStorageGatewayNfsFileShare_KMSEncrypted|TestAccAWSStorageGatewayNfsFileShare_NFSFileShareDefaults|TestAccAWSStorageGatewayNfsFileShare_ObjectACL|TestAccAWSStorageGatewayNfsFileShare_ReadOnly|TestAccAWSStorageGatewayNfsFileShare_RequesterPays)'
triggering refs/pull/12530/merge for (TestAccAWSStorageGatewayNfsFileShare_KMSEncrypted|TestAccAWSStorageGatewayNfsFileShare_NFSFileShareDefaults|TestAccAWSStorageGatewayNfsFileShare_ObjectACL|TestAccAWSStorageGatewayNfsFileShare_ReadOnly|TestAccAWSStorageGatewayNfsFileShare_RequesterPays)...
  bflad@HOSTNAME#Aws_ProviderAwsAlternate
  build 103998 queued: https://HOSTNAME/viewQueued.html?itemId=103998

It'd be really nice if we could so something like the following instead:

$ tctest run-failed-results 103995
# or
$ tctest pr --failed-only 12530
# or
$ tctest pr --run-failed-results=103995 12530

[bflad]

Hacky one liner workaround:

$ tctest pr 12530 $(tctest results 103995 | grep -E -e "^--- FAIL:" | cut -d' ' -f 3 | tr '\n' '|' | sed -e 's/|$//')

I'm guessing there could other potential enhancement ideas here such as:

$ tctest results --failed-only --names-only 103995