feat: allow bridge protocol versions in packet generation

[seriousme]

This PR allows bride protocol versions (MQTT protocol+128) to be generated as discussed in moscajs/aedes#1042 (review)

[robertsLando]

LGTM

[robertsLando]

Cool enough seems this spec is not present anywhere on MQTT specs, but can be found in other MQTT modules like: https://github.com/eclipse-mosquitto/mosquitto/blob/3cbe805e71ac41a2a20cc9b2ea6b3b619f49554a/lib/send_connect.c#L153

[seriousme]

Indeed, it seems to be convention and not part of the formal spec.

[seriousme]

The parser already supports it:

mqtt-packet/parser.js

Lines 171 to 173 in e39fb28

	if (packet.protocolVersion >= 128) {
	packet.bridgeMode = true
	packet.protocolVersion = packet.protocolVersion - 128

Looking at the parser we might want to make it symmetrical and use:

protocolVersion: 4
bridgeMode: true

during generation as well.
Which seems a better solution than my current fix.

[robertsLando]

@seriousme yep agree, go for that

[seriousme]

I will push an update later today.

[seriousme]

I did some more research and the feature was already present:

mqtt-packet/writeToStream.js

Lines 225 to 227 in e39fb28

	if (settings.bridgeMode) {
	protocolVersion += 128
	}

So we can close this PR.