EnvoyFilter builder

[strekm]

Description

Implement abstraction for building EnvoyFilter to support rate limiting. EnvoyFilter is complex CR for wide range of tasks in Istio. Implementation should be focused on Rate Limiting story local scenario. The builder later on will be used in reconciliation of RateLimiting CR. Have in mind that minimal implementation is limited but it will be extended so implementation should be flexible.

AC:

• EnvoyFilter builder introduced

TODOs:

• Create EnvoyFilter Builder
• Create local RateLimit builder for EnvoyFilter
• Implement unit tests

Reasons

DoD:

• Provide unit and integration tests.
• Provide documentation.
• Verify if the solution works for both open-source Kyma and SAP BTP, Kyma runtime.
• If you changed the resource limits, explain why it was needed.
• Verify that your contributions don't decrease code coverage. If they do, explain why this is the case.
• Add release notes.

Attachments
https://github.com/kyma-project/istio/blob/main/docs/contributor/adr/0008-rate-limit.md
part of: #1365