Add role_attribute_strict flag in generic/okta oauth config

[4n4nd]

Description

Add role_attribute_strict bool flag in the generic and okta oauth configs.
This was added in upstream grafana in the following PR: grafana/grafana#28021

Relevant issues/tickets

Resolves #498

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. Deploy Operator
2. Deploy Grafana
3. Add the following in grafana resource

config:
    auth.generic_oauth:
      enabled: true
      role_attribute_strict: true

4. The created grafana container should have a grafana.ini with the following string role_attribute_strict: true

[HVBE]

/lgtm

/approve

Thanks for contributing @4n4nd 👍 , changes work as expected, the configmap is populated with the values defined in the example