fix(codec): Enforce encoders/decoders are Sync

[LucioFranco]

cc @NeoLegends

Closes #81

[LucioFranco]

Yeah...this will be a bit harder than anticipated...

[NeoLegends]

Yeah, this is the other option. I guess you're in the best position to know which bounds you will be able to satisfy in tonic.

For this implementation route we'd also want to add a test that ensures Streaming stays sync (when adding new members).

You might also want to add a Closes #82 to close the other PR automatically when this one is merged. I'll do the opposite on the other one.

[LucioFranco]

@seanmonstar would you be able to take a look at this?

[seanmonstar]

What I'm about to say sounds dumb: for trait objects, the order of additional auto traits matters, and most places write them as dyn Foo + Send + Sync. That's to say, dyn Foo + Sync + Send isn't the same thing. 😭

[LucioFranco]

@seanmonstar all i can say is lol

[NeoLegends]

Does this put #82 back on the table?

[LucioFranco]

@NeoLegends we still want to go with this one but need to change the order of the bounds.

[LucioFranco]

@seanmonstar can I get your +1 on this before we merge?