dnsdist: Add Lua bindings for PB requestorID, deviceName and deviceID

[rgacogne]

Short description

I forgot to add these before, and they are already used by the recursor.

Checklist

I have:

• read the CONTRIBUTING.md document
• compiled this code
• tested this code
• included documentation (including possible behaviour changes)
• documented the code
• added or modified regression test(s)
• added or modified unit test(s)

[omoerbeek]

Two remarks, reads good.

[omoerbeek]

in the from field.

[rgacogne]

Isn't that in the requestorId field?

[omoerbeek]

Hmm, right. I mixed that field up with d_requestor used in the m.setRequest call. These names are too similar :-(

[rgacogne]

You are right, requestorId did not exist initially but now it's confusing indeed.

[omoerbeek]

I do not like this "do nothing silently" much. Wouldn't be better to indicate failure to set with a bool return value? I see that this void return value for setters is common, so something for the future to consider. Another thing to consider: the testing for dq and dq->value is not done in all setters.

[rgacogne]

I agree this isn't great. We have added these checks after noticing that crashing dnsdist because of a typo in the Lua code was terrible (a nil value becomes a nullptr).
Yielding an exception in the FFI API doesn't work well at the moment, so we could indeed return a boolean instead, but it would make handling the potential errors in the Lua code quite cumbersome.