resource/aws_iam_role: Ensure resource recreates when deleted outside Terraform

[bflad]

Changes proposed in this pull request:

• Appropriately tests the line that has XXX test me from the resource so we can remove it 😉
• Also prevent potential panics in case the API not returning the actual response or nested response object

Output from acceptance testing:

$ make testacc TEST=./aws TESTARGS='-run=TestAccAWSIAMRole_'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./aws -v -run=TestAccAWSIAMRole_ -timeout 120m
=== RUN   TestAccAWSIAMRole_importBasic
--- PASS: TestAccAWSIAMRole_importBasic (11.45s)
=== RUN   TestAccAWSIAMRole_basic
--- PASS: TestAccAWSIAMRole_basic (9.13s)
=== RUN   TestAccAWSIAMRole_basicWithDescription
--- PASS: TestAccAWSIAMRole_basicWithDescription (24.04s)
=== RUN   TestAccAWSIAMRole_namePrefix
--- PASS: TestAccAWSIAMRole_namePrefix (10.40s)
=== RUN   TestAccAWSIAMRole_testNameChange
--- PASS: TestAccAWSIAMRole_testNameChange (20.12s)
=== RUN   TestAccAWSIAMRole_badJSON
--- PASS: TestAccAWSIAMRole_badJSON (1.44s)
=== RUN   TestAccAWSIAMRole_disappears
--- PASS: TestAccAWSIAMRole_disappears (7.60s)
=== RUN   TestAccAWSIAMRole_force_detach_policies
--- PASS: TestAccAWSIAMRole_force_detach_policies (11.82s)
=== RUN   TestAccAWSIAMRole_MaxSessionDuration
--- PASS: TestAccAWSIAMRole_MaxSessionDuration (18.99s)
=== RUN   TestAccAWSIAMRole_PermissionsBoundary
--- PASS: TestAccAWSIAMRole_PermissionsBoundary (32.31s)
PASS
ok  	github.com/terraform-providers/terraform-provider-aws/aws	147.937s

[catsby]

👍

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!