Adding Topology Spread Constraints to Grafana CR

[celestialorb]

Description

Adds specification of topology spread constraints to a managed Grafana deployment.

Relevant issues/tickets

Closes #834.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• This change requires a documentation update
• I have added tests that prove my fix is effective or that my feature works
• I have added a test case that will be used to verify my changes
• Verified independently on a cluster by reviewer

Verification steps

1. With the Grafana operator running against a cluster, add a Grafana CR without TopologySpreadConstraints defined in the deployment specification.
2. Ensure the resultant Grafana deployment contains no topology spread constraints.
3. Specify a Grafana CR with some arbitrary TopologySpreadConstraints defined.
4. Ensure the resultant Grafana deployment contains the same topology spread constraints.

[NissesSenap]

Sorry for the slow reply @celestialorb , I will fix the CI issues in your PR. Other then that I think everything looks good :)