Feature: More complete ATT protocol

[fmckeogh]

Very much a WIP.

Opened a PR because I could use some guidance on if there could be a nicer way to get the slice out of a HexSlice other than hex_slice.0?

TODO:

• [x] Add all messages to AttMsg<'a> enum
• [x] ToBytes/FromBytes for IncomingPdu/OutgoingPdu
• [ ] Add functionality for all messages to fn process_request for AttributeServer<A> Not needed for this to land

[jonas-schievink]

if there could be a nicer way to get the slice out of a HexSlice other than hex_slice.0?

There doesn't seem to be one right now (which is why that field is pub), but you can add one if you want

[fmckeogh]

Progress! Found the culprit as to why I wasn't seeing the requests I expected ;)

https://github.com/jonas-schievink/rubble/blob/14a09fd6626ce134ebe9da3910312600e548bf3f/rubble/src/att/mod.rs#L573

But I'm back on track now :)

[fmckeogh]

It might be easier to split up this PR into multiple smaller ones, if so, this is ready for review and merging.

[jonas-schievink]

The problems when trying to read values are caused by https://github.com/jamesmunns/bbqueue/issues/29 – they shouldn't block landing this though.