iBeacon: Flag to use UUID in topic or presence (and fixes)

[BadWolf42]

Description:

Inspired by issue #1139
Replaces PR #1220

Add compilation flags to use UUID in topic, instead of sender (random) mac address:
FLAG useBeaconUuidForTopic to use UUID in topic
FLAG useBeaconUuidForPresence to use UUID in presence
This features is disabled by default, usual behavior is maintained
The question of whitelisting/blacklisting by UUID for a iBeacon, as exposed in the issue, is not approached in this commit.
(WhtL/BlkL is filtered prior to pubBTMainCore() function, so it does not seems to be as simple as this PR)

Change introduced regarding MQTTDecodeTopic and code refactor
Fix jsonPublishing (regarding #1141?) there is an #ifdef left here that should be an #if

Checklist:

• The pull request is done against the latest development branch
• Only one feature/fix was added per PR and the code change compiles without warnings
• I accept the DCO.

Thanks, Bad

[1technophile]

Thanks