[Feature Request] Let me specify the encoding for my inputs. Bonus for doing this with outputs too...

Is your feature request related to a problem? Please describe.

We are too assumptive about JSON usage everywhere...We need to support arbitrary encodings for at least inputs (if not outputs also...) , for example encoding=json/protobuf.

We support this on some commands while others we do not.

Describe the solution you'd like

Support protobufs for real from the CLI since we include it as default data converter in most SDKs OOTB.

We really should allow specifying the OUTPUT encoding too since protobufs are a result too, not just an input. Basically, these commands need to be consistency and real-world.

Additional context

I did the hard part for you in identifying which commands lack proper support for input encoding:

Category	Command	Payload Flag	Meta/Encoding Switch?
Workflow	start / execute	--input	Yes (--input-meta)
Workflow	update start	--input	Yes (--input-meta)
Workflow	signal	--input	No
Workflow	query	--input	No
Activity	complete	--result	No
Activity	fail	--detail	No
Activity	heartbeat	--details	No
Batch	signal	--input	No
Schedule	create / update	--input	Yes (--input-meta)