Add optional alerts validations

[assafad]

Add the following custom alert validations:

• Validation for limiting alerts names length to 50 characters. We want to prevent alerts names from being too long, so they will fit on the TOC in the docs.
• Validation for the existence of runbook_url annotation.
• Validation for existence of operator_health_impact, kubernetes_operator_part_of and kubernetes_operator_component labels.

Fixes https://issues.redhat.com/browse/CNV-31132.

[sradco]

@assafad please update the PR description and add the link to Jira in a separate line.

[assafad]

@assafad please update the PR description and add the link to Jira in a separate line.

Done.

[machadovilaca]

please add a unit test for this verification

also, do you think this should be a mandatory rule for every operator that uses this library, or it should be optional?

[sradco]

please add a unit test for this verification

also, do you think this should be a mandatory rule for every operator that uses this library, or it should be optional?

I think we should make it optional.

[machadovilaca]

thank you for the PR and for the fixes in the previous code
good work