This resource will enable exclusive management of inline policy assignments to an IAM role. This functions similar to the `inline_policy` blocks when defined on the `aws_iam_role` resource, but as a standalone resource.

```console
% make testacc PKG=iam TESTS=TestAccIAMRolePoliciesExclusive_
make: Verifying source code with gofmt...
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go1.23.0 test ./internal/service/iam/... -v -count 1 -parallel 20 -run='TestAccIAMRolePoliciesExclusive_'  -timeout 360m

--- PASS: TestAccIAMRolePoliciesExclusive_empty (13.72s)
--- PASS: TestAccIAMRolePoliciesExclusive_disappears_Role (13.72s)
--- PASS: TestAccIAMRolePoliciesExclusive_basic (15.84s)
--- PASS: TestAccIAMRolePoliciesExclusive_multiple (24.25s)
PASS
ok      github.com/hashicorp/terraform-provider-aws/internal/service/iam        30.454s
```

With the introduction of the `aws_iam_role_policies_exclusive` resource, the provider now has parity with the behavior of the existing `inline_policy` argument. To encourage a single pattern for managing inline policy associations, the inline argument on the role resource is now deprecated. Due to this resources popularity it is undetermined whether the argument will be fully removed in a future major version, but the deprecation warning allows maintainers to direct users to a preferred pattern.

Adds tests to cover out of band additions and removals of inline policies.

```console
% make testacc PKG=iam TESTS=TestAccIAMRolePoliciesExclusive_
make: Verifying source code with gofmt...
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go1.22.6 test ./internal/service/iam/... -v -count 1 -parallel 20 -run='TestAccIAMRolePoliciesExclusive_'  -timeout 360m

--- PASS: TestAccIAMRolePoliciesExclusive_empty (15.28s)
--- PASS: TestAccIAMRolePoliciesExclusive_disappears_Role (15.33s)
--- PASS: TestAccIAMRolePoliciesExclusive_basic (17.58s)
--- PASS: TestAccIAMRolePoliciesExclusive_outOfBandAddition (24.33s)
--- PASS: TestAccIAMRolePoliciesExclusive_outOfBandRemoval (24.34s)
--- PASS: TestAccIAMRolePoliciesExclusive_multiple (26.37s)
PASS
ok      github.com/hashicorp/terraform-provider-aws/internal/service/iam        32.643s
```