fix(entity_tags): fixed improper error handling in newrelic_entity_tags resource

[shashank-reddy-nr]

Description

Currently, In newrelic_entity_tags resource there is improper error handling when we try to update reserved tags(default tags which will be added when we create entity). Please check out the below JIRA ticket for more info.

JIRA Ticket: https://new-relic.atlassian.net/browse/NR-273648

Fixes

Added a new function CreateErrorDiagnostics which will print all errors if present in the response called nerdgraph APIs. The CreateErrorDiagnostics function is called in resourceNewRelicEntityTagsCreate, resourceNewRelicEntityTagsUpdate, resourceNewRelicEntityTagsDelete.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

Checklist:

Please delete options that are not relevant.

• My commit message follows conventional commits
• My code is formatted to Go standards
• I have performed a self-review of my own code
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes. Go here for instructions on running tests locally.

[pranav-new-relic]

@shashank-reddy-nr if you find we have no relevant test cases that validate errors thrown inside the response body of entity tags create and update mutations, can you please add a relevant test case which throws the error you've added (and can be validated by regex of the error)

[pranav-new-relic]

@shashank-reddy-nr please also add a note to the docs of this resource stating that modifying values of restricted tags is not supported by the create and update mutations; consequently, this is not supported by this resource as well - you can add this link as a reference to these restricted tags

[shashank-reddy-nr]

@shashank-reddy-nr if you find we have no relevant test cases that validate errors thrown inside the response body of entity tags create and update mutations, can you please add a relevant test case which throws the error you've added (and can be validated by regex of the error)

Added integration test cases to validate errors thrown : newrelic/newrelic-client-go#1188