[enhancement] Secret type should have default of `null` or `Opaque` per rancher2 provider reference docs

[paraglade]

if not provided a default should be set for secret type: https://github.com/rancher/terraform-rancher2-project/blob/master/locals.tf#L49

rancher2 provider reference docs will use Opaque when invoking the resource directly: https://registry.terraform.io/providers/rancher/rancher2/latest/docs/resources/secret_v2#:~:text=and%20expected%20format.%20Default%3A%20Opaque%20(string)

[rawmind0]

@paraglade , the default secret type is already set to opaque if not provided. As you mentioned, the Rancher2 tf provider is setting it as opaque by default.