helper/schema: Ensure (ResourceData).GetRawConfig() is populated in provider Configure functions

[bflad]

Closes #1270

This change is intended to be as targeted as possible to prevent other unintended changes. In other RPCs, the protocol configuration data is able to be set upfront via terraform.InstanceState, however for provider configuration it is still using the legacy terraform.ResourceConfig value which previously did not have the same data field. This adds the data field while trying to be pragmatic about potentially breaking compatibility with the unfortunately exported APIs in this SDK.

This change also tangentially fixes GetOkExists to now return a true second result when a configuration

New test failures prior to updating logic:

--- FAIL: TestProviderConfigure (0.00s)
    --- FAIL: TestProviderConfigure/ConfigureContextFunc-GetRawConfig (0.00s)
        /Users/bflad/src/github.com/hashicorp/terraform-plugin-sdk/helper/schema/provider_test.go:338: Unexpected diagnostics (-wanted +got):   diag.Diagnostics(
            -   nil,
            +   {{Summary: "unexpected GetRawConfig difference: expected: {{{{} map[test:{{{"...}},
              )
    --- FAIL: TestProviderConfigure/ConfigureFunc-GetRawConfig (0.00s)
        /Users/bflad/src/github.com/hashicorp/terraform-plugin-sdk/helper/schema/provider_test.go:338: Unexpected diagnostics (-wanted +got):   diag.Diagnostics(
            -   nil,
            +   {{Summary: "unexpected GetRawConfig difference: expected: {{{{} map[test:{{{"...}},
              )

--- FAIL: TestGRPCProviderServerConfigureProvider (0.00s)
    --- FAIL: TestGRPCProviderServerConfigureProvider/ConfigureContextFunc-GetRawConfig (0.00s)
        /Users/bflad/src/github.com/hashicorp/terraform-plugin-sdk/helper/schema/grpc_provider_test.go:343: unexpected difference:   &tfprotov5.ConfigureProviderResponse{
            -   Diagnostics: []*tfprotov5.Diagnostic{
            -       &{
            -           Severity: s"ERROR",
            -           Summary:  "unexpected difference: expected: {{{{} map[test:{{{} %!s(cty.pri"...,
            -       },
            -   },
            +   Diagnostics: nil,
              }
    --- FAIL: TestGRPCProviderServerConfigureProvider/ConfigureFunc-GetRawConfig (0.00s)
        /Users/bflad/src/github.com/hashicorp/terraform-plugin-sdk/helper/schema/grpc_provider_test.go:343: unexpected difference:   &tfprotov5.ConfigureProviderResponse{
            -   Diagnostics: []*tfprotov5.Diagnostic{
            -       &{
            -           Severity: s"ERROR",
            -           Summary:  "unexpected difference: expected: {{{{} map[test:{{{} %!s(cty.pri"...,
            -       },
            -   },
            +   Diagnostics: nil,
              }

In terms of prior (errant) GetOkExists() behavior, this causes this behavior change/fix:

--- FAIL: TestProviderConfigure (0.00s)
    --- FAIL: TestProviderConfigure/ConfigureContextFunc-GetOkExists-zero-value (0.00s)
        /Users/bflad/src/github.com/hashicorp/terraform-plugin-sdk/helper/schema/provider_test.go:924: Unexpected diagnostics (-wanted +got):   diag.Diagnostics(
            -   nil,
            +   {{Summary: "unexpected GetOkExists difference: expected: false, got: true"}},
              )
    --- FAIL: TestProviderConfigure/ConfigureFunc-GetOkExists-zero-value (0.00s)
        /Users/bflad/src/github.com/hashicorp/terraform-plugin-sdk/helper/schema/provider_test.go:924: Unexpected diagnostics (-wanted +got):   diag.Diagnostics(
            -   nil,
            +   {{Summary: "unexpected GetOkExists difference: expected: false, got: true"}},
              )

[bflad]

one general question, the linked issue also mentions GetRawPlan and GetRawState, are we going to eventually populate those as well?

Provider configuration only contains configuration data. It does not participate in the plan (similar to data sources) nor does Terraform preserve a prior state.

[github-actions[bot]]

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