feat: add coverage report to PRs

[andreaangiolillo]

Description

This PR updates the unit-test action to generate and include the coverage report in the PR.

This change was discussed as part of the Engineering Proposal (comment)

Note:

Once the PR is merged, the following PRs will get an additional Column Branch Rate that shows the coverage in the branch vs PR as shown in https://github.com/irongut/CodeCoverageSummary#markdown-example

Link to any related issue(s):

Type of change:

• Bug fix (non-breaking change which fixes an issue). Please, add the "bug" label to the PR.
• New feature (non-breaking change which adds functionality). Please, add the "enhancement" label to the PR.
• Breaking change (fix or feature that would cause existing functionality to not work as expected). Please, add the "breaking change" label to the PR.
• This change requires a documentation update
• Documentation fix/enhancement

Required Checklist:

• I have signed the MongoDB CLA
• I have read the contribution guidelines
• I have added tests that prove my fix is effective or that my feature works per HashiCorp requirements
• I have added any necessary documentation (if appropriate)
• I have run make fmt and formatted my code
• If changes include deprecations or removals, I defined an isolated PR with a relevant title as it will be used in the auto-generated changelog.

Further comments

[github-actions]

Package	Line Rate	Health
github.com/mongodb/terraform-provider-mongodbatlas/mongodbatlas	2%	❌
github.com/mongodb/terraform-provider-mongodbatlas/mongodbatlas/framework/validator	68%	➖
github.com/mongodb/terraform-provider-mongodbatlas/mongodbatlas/util	20%	❌
Summary	3% (279 / 10571)	❌

[marcosuma]

LGTM

[maastha]

Does this include coverage via acceptance tests as well or only unit tests? Because we mainly have acceptance tests

[andreaangiolillo]

Does this include coverage via acceptance tests as well or only unit tests? Because we mainly have acceptance tests

Unit tests as they are the ones that run for all the PRs. Having something similar for acceptance tests would mean running all the acceptance tests for all the PRs at all times which is something that we don't want to do. Feel free to create a ticket to investigate a way to include acceptance test coverage if you think we should do it