Issue #487: set default ingress path

[vmanley]

Description

Sets default path (/) when creating an ingress and no explicit path is set by user

Relevant issues/tickets

#487

Type of change

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

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

• Operator deployed locally with using example Grafana instance with path: " " in spec.ingress
• Grafana ingress object should contain default path of path: /