feat: support JSONPatch in ModelSpec

[liebman]

This PR adds JSONPatch support to the Model CRD.

There is difficulty representing the Value field in JSONPatch, its a go interface{} but there seems to be no type to map it to in CRDs. So this is implemented as a string expected to contain the JSON encoded value, For instance if the value is a string: "\"this-is-a string-value\""

[liebman]

I added a test that tries to set a string value and as expected when defining the Type as object it fails

    model_jsonpatch_test.go:40: 
                Error Trace:    kubeai/test/integration/model_jsonpatch_test.go:40
                Error:          Received unexpected error:
                                Model.kubeai.org "testjsonpatch" is invalid: [spec.jsonPatches[0].value: Invalid value: "string": spec.jsonPatches[0].value in body must be of type object: "string", <nil>: Invalid value: "null": some validation rules were not checked because the object was invalid; correct the existing errors to complete validation]
                Test:           TestJSONPatch

If I don't set a Type it errors loading the CRD complaining there is no type.

[liebman]

@nstogner any ideas on how to declare the Value field?

[liebman]

The only way I can think of to make this work is to store Value as a string containing json. So a string value would be encoded as ""string-value"", an integer as "123" and an object as "{"something": 42}" and I don't like it as it's not what the user would expect, especially in a Model yaml file, the value would still need to be a encoded as json in a string.

[liebman]

Implemented where JSONPatch.value is a string expected to contain valid JSON.