Invalid k8s annotations are not cause error and simply ignored.

[Hosshii]

What would you like to be added: k8s(and other kinds of application) spec validation.

Why is this needed: Following spec is invalid because while annotations' key and value must be string, ture is treated as bool.

apiVersion: apps/v1
kind: Deployment
metadata:
  annotations:
    pipecd.dev/sync-by-replace: true # must be "true"
...

But the spec like this are not cause validation error, and the invalid annotations are simply ignored.