Create acceptance tests for ably_app resource

[graham-russell]

• Uses the terraform SDKv2 acceptance test framework.
• Includes tests for provider + ably_app.
• Ran go mod tidy to update dependencies after implementing tf acceptance tests.
• Also updated Makefile to fix NAME var.

You can run the acceptance tests locally for now using make testacc. You will need Ably credentials set as env vars. GHA Workflow coming in separate step.

[graham-russell]

Example test output

TF_ACC=1 go test $(go list ./... | grep -v 'vendor') -v  -timeout 120m
?       terraform-provider-ably [no test files]
=== RUN   TestAccAblyApp
--- PASS: TestAccAblyApp (11.64s)
=== RUN   TestAccAblyAppDisabledStatus
    resource_ably_app_test.go:47: Step 1/1 error: Error running apply: exit status 1

        Error: Provider produced inconsistent result after apply

        When applying changes to ably_app.app0, provider
        "provider[\"github.com/ably/ably\"]" produced an unexpected new value:
        .status: was cty.StringVal("disabled"), but now cty.StringVal("enabled").

        This is a bug in the provider, which should be reported in the provider's own
        issue tracker.
--- FAIL: TestAccAblyAppDisabledStatus (4.37s)
FAIL
FAIL    terraform-provider-ably/internal/provider       16.305s
FAIL
make: *** [testacc] Error 1

[kavalerov]

It is failing right now when ABLY_URL is not set - should it just fall back to default URL when no env var is set?

[graham-russell]

It is failing right now when ABLY_URL is not set - should it just fall back to default URL when no env var is set?

I have now removed ABLY_URL env var check from the test pre-checks.