Resource Modifier should support json merge patch and strategic merge patch

[27149chen]

Describe the problem/challenge you have
Resource Modifier uses json patch to patch object, but json patch is not easy to use and has limitations.
For example:

1. if I want to remove an annotation not matter it exists or not, a json merge patch is better ({"metadata":{"annotations":{"foo":null}}})
2. if I want to update a container image by container name, a strategic merge patch should be used

Describe the solution you'd like
support json merge patch and strategic merge patch in Resource Modifier

Anything else you would like to add:

Environment:

• Velero version (use velero version):
• Kubernetes version (use kubectl version):
• Kubernetes installer & version:
• Cloud provider or hardware configuration:
• OS (e.g. from /etc/os-release):

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[anshulahuja98]

#6344
#6344 (comment) what are your thoughts on leveraging jq instead to give such capabilities, while possibly keeping the jsonpatch setup intact.

CC @qiuming-best

[27149chen]

I think they are different things, jq can not cover the capabilities which json merge patch or strategic merge patch can provide

[27149chen]

@reasonerjt I want to implement this feature, can you assign it to me?

[anshulahuja98]

@27149chen I think it would be great if you could pick impl. I can assign it to you.
Can we meanwhile further close on the approach over slack?
https://kubernetes.slack.com/archives/C021GPR1L3S/p1693808146936179

Had put further points on this, I am trying to see if through whatever enhancements we do to resource modifiers, we are also able to support scenarios in #6344

[ywk253100]

Reopen it as the implementation isn't merged