provider/aws: aws_route53_record import error processing (#11603)

Fixes: #11549

When a user passes the wrong argument to a route53_record import, they
got a crash. This was because we expected the ID to parse correctly. The
crash looked like this:

```
% terraform import aws_route53_record.import1 mike.westredd.com
aws_route53_record.import1: Importing from ID "mike.westredd.com"...
aws_route53_record.import1: Import complete!
  Imported aws_route53_record (ID: mike.westredd.com)
aws_route53_record.import1: Refreshing state... (ID: mike.westredd.com)
Error importing: 1 error(s) occurred:

* aws_route53_record.import1: unexpected EOF
panic: runtime error: index out of range
```

Rather than throwing a panic to the user, we should present them with a more useful message that tells them what the error is:

```
% terraform import aws_route53_record.import mike.westredd.com
aws_route53_record.import: Importing from ID "mike.westredd.com"...
aws_route53_record.import: Import complete!
  Imported aws_route53_record (ID: mike.westredd.com)
aws_route53_record.import: Refreshing state... (ID: mike.westredd.com)
Error importing: 1 error(s) occurred:

* aws_route53_record.import: Error Importing aws_route_53 record. Please make sure the record ID is in the form ZONEID_RECORDNAME_TYPE (i.e. Z4KAPRWWNC7JR_dev_A
```

At least they can work out what the problem is in this case

builtin/providers/aws/resource_aws_route53_record.go

@@ -459,6 +459,11 @@ func resourceAwsRoute53RecordRead(d *schema.ResourceData, meta interface{}) erro
 	// If we don't have a zone ID we're doing an import. Parse it from the ID.
 	if _, ok := d.GetOk("zone_id"); !ok {
 		parts := strings.Split(d.Id(), "_")
+
+		if len(parts) == 1 {
+			return fmt.Errorf("Error Importing aws_route_53 record. Please make sure the record ID is in the form ZONEID_RECORDNAME_TYPE (i.e. Z4KAPRWWNC7JR_dev_A")
+		}
+
 		d.Set("zone_id", parts[0])
 		d.Set("name", parts[1])
 		d.Set("type", parts[2])