feat: allow ignoring prefixes

[busser]

Add a new prefix rule. For example, if tfautomv's analysis displays this difference:

Mismatch: google_storage_bucket_iam_member.example
╷
│ + bucket = "my-bucket"
│ - bucket = "b/my-bucket"
╵

Then users can add this flag to ignore this difference:

tfautomv -ignore "prefix:google_storage_bucket_iam_member:bucket:b/"