Provide a mechanism to override the configurations of a proxy during linkerd inject. By default, if no flags are provided, the proxy will inherit the configurations specified in the linkerd-config config map during CLI inject. If present, the config flags should be converted into annotations on the pod spec before being passed to the proxy-injector. The proxy-injector will then perform the configs overrides per #2287.

Depending on whether the YAML defines a single pod or a workflow resource, the CLI will have to insert the annotations at different levels (i.e. metadata.annotations and spec.template.metadata.annotations).

Depends on #2287.