Add reflection tests for object models with tfsdk tags in framework providers

[austinvalle]

Ref: hashicorp/terraform-plugin-framework#1021

Since we're adding support for embedded struct support for tfsdk tags, I added some smoke tests for relatively complex struct models for both getting/setting values. I covered most types when writing the test, but the intention of this test is really to ensure values are set/retrieved correctly and not the individual type implementations themselves.