Add conversion to protobuf for most core types

[XAMPPRocky]

This splits out most of the type conversion code from #506 in order to make it easier to review and merge.``

[markmandel]

Thanks for breaking this out - made it much easier to review.

[quilkin-bot]

Build Succeeded 🥳

Build Id: 8d18dc7a-1442-4428-af8a-10ec015c045b

To build this version:

git fetch git@github.com:googleforgames/quilkin.git pull/514/head:pr_514 && git checkout pr_514
cargo build

[markmandel]

Not sure if I was clear in the above comment which was resolved.

I was suggesting that we should follow the same pattern of using the proto import alias as we have elsewhere in this PR for this file as well for consistency (and I like the pattern better).

So this should become:

Suggested change

	impl From<Mode> for ProtoMode {
	impl From<Mode> for proto::Mode {

and so on and so forth for the other items in this file as well.

[XAMPPRocky]

The problem with doing it for these types, is that they're embedded within the compress message namespace, so it would be proto::compress::Mode::Snappy for example rather than proto::Mode::Snappy. I could move the types outside the message in their Protobuf definition to fix that, but I wanted to make sure separately that that's what we want to do here separately.

[markmandel]

Got it - that makes sense. Thanks for the explanation. Approval from me then 👍🏻