serverSideApply dsl support

[shawkins]

Description

Implementation of serverSideApply described in #4524 (comment)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• Feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change
• Chore (non-breaking change which doesn't affect codebase;
  test, version modification, documentation, etc.)

Checklist

• Code contributed by me aligns with current project license: Apache 2.0
• I Added CHANGELOG entry regarding this change
• I have implemented unit tests to cover my changes
• I have added/updated the javadocs and other documentation accordingly
• No new bugs, code smells, etc. in SonarCloud report
• I tested my code in Kubernetes
• I tested my code in OpenShift

[sonarcloud]

SonarCloud Quality Gate failed.   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
1 Code Smell

78.0% Coverage
0.0% Duplication

[bachmanity1]

It looks like it's not possible to test this method with a mock server using @EnableKubernetesMockClient(crud = true). The mock server returns 404 error unless resource is created in advance. This behavior doesn't match the behavior of real k8s server which doesn't return an error but creates a resource if it doesn't already exist.

[bachmanity1]

It looks like it's not possible to test this method with mock server using @EnableKubernetesMockClient(crud = true). Mock server returns 404 error unless resource is created in advance. This behavior doesn't match behavior of real k8s server which doesn't return error but creates a resource if doesn't already exist.

actually, this doesn't work even if a resource is created in advance. I get Unsupported Media Type error.

io.fabric8.kubernetes.client.KubernetesClientException: Failure executing: PATCH at: 
https://localhost:60043/apis/foo/v1/namespaces/test/foos/test?fieldManager=fabric8&force=true. Message: Unsupported 
Media Type. Received status: Status(apiVersion=v1, code=415, details=StatusDetails(causes=[], group=null, 
kind=Unknown, name=null, retryAfterSeconds=null, uid=null, additionalProperties={}), kind=Status, 
message=Unsupported Media Type, metadata=null, reason=Invalid, status=Failure, additionalProperties={}).

[shawkins]

actually, this doesn't work even if a resource is created in advance. I get Unsupported Media Type error.

The crud mock server does not support server side apply.