fix: handling of errors for services, subscriptions and bindings

[lechnerc77]

Purpose

• Fix handling of errors during CRUD operations on app subscriptions, service instances and service bindings by explicitly handling failure state as no error is returned by API
• closes [BUG] failed app subscription not detected for SAP Build Apps #351

Does this introduce a breaking change?

[ ] Yes
[X] No

Pull Request Type

What kind of change does this Pull Request introduce?

[X] Bugfix
[ ] Feature
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

How to Test

• Test the code via automated test

go test ./...

What to Check

Verify that the following are valid:

• Automated tests are executed successfully

Other Information

n/a

Checklist for reviewer

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• The PR is assigned to the Terraform project and a status is set (typically "in review").
• The PR has the matching labels assigned to it.
• The PR has a milestone assigned to it.
• If the PR closes an issue, the issue is referenced.
• Possible follow-up items are created and linked.

[rui1610]

Thanks for fixing it so quickly!