Replace github OTA update over MQTT with settings in user_config.

[h2zero]

This removes the github certificate header and incorporates it into user_config.

• User_config has been slightly refactored to consolidate definitions into a more appropriate location.
• MQTT_HTTPS_FW_UPDATE has been renamed to MQTT_HTTPS_OTA_UPDATE for consitency.
• MQTT_HTTPS_FW_UPDATE_USE_PASSWORD has been renamed to MQTT_HTTPS_OTA_UPDATE_USE_PASSWORD for consistency.
• CI builds updated to reflect the above changes.

[NorthernMan54]

@h2zero I just refreshed my development environment with the most recent changes and am thinking either this pull request, #971 or #961 has introduced an issue with setting up the MQTT connection when using MDNS based Mqtt host discovery. I'm still troubleshooting the issue but something introduced to main.ino since May 28th has caused my config to stop working

Did you do any testing with MDNS based MQTT Host discovery?

************* WELCOME TO OpenMQTTGateway **************
N: OpenMQTTGateway Version: ddd-bt-rtl-v0.9.6-34-g2737a4c[dev-june-8]
T: Connecting to 67 Bonacres
T: Connecting to The_Beach
N: WiFi ok with manual config credentials
T: OpenMQTTGateway mac: 24:0A:C4:EC:20:DC
T: OpenMQTTGateway ip: 192.168.1.181
T: Connecting to MQTT by mDNS without mqtt hostname
T: Browsing for MQTT service
T: 1 service(s) found
T: Service 0 jesse found
T: IP 192.168.1.11 Port 1883
T: One MQTT server found setting parameters
N: BLE scans interval: 0
N: BLE scans number before connect: 10
N: Publishing only BLE sensors: true
N: minrssi: 100
N: Low Power Mode: 0
T: ZgatewayBT multicore ESP32 setup done 
T: mqtt_max_packet_size: 1024
N: OpenMQTTGateway modules: ["BT"]
N: ************** Setup OpenMQTTGateway end **************
W: MQTT connection...
Guru Meditation Error: Core  1 panic'ed (LoadProhibited). Exception was unhandled.
Core 1 register dump:
PC      : 0x400ddce9  PS      : 0x00060e30  A0      : 0x800ddf90  A1      : 0x3ffcda60  
A2      : 0x3ffc33b0  A3      : 0x3ffbdc44  A4      : 0x3ffbdd48  A5      : 0x3ffbdd0c  
A6      : 0x3ffcdae4  A7      : 0x00000000  A8      : 0x800ddce2  A9      : 0x3ffcda40  
A10     : 0x00000000  A11     : 0x00000001  A12     : 0x00000400  A13     : 0x00000008  
A14     : 0x00000000  A15     : 0x00000000  SAR     : 0x0000001e  EXCCAUSE: 0x0000001c  
EXCVADDR: 0x00000000  LBEG    : 0x4000c2e0  LEND    : 0x4000c2f6  LCOUNT  : 0x00000000  

ELF file SHA256: 0000000000000000

Backtrace: 0x400ddce9:0x3ffcda60 0x400ddf8d:0x3ffcdaa0 0x400d3108:0x3ffcdad0 0x400dd7a8:0x3ffcdbd0 0x400fd55d:0x3ffcdbf0 0x40090d3e:0x3ffcdc10
  #0  0x400ddce9:0x3ffcda60 in PubSubClient::connect(char const*, char const*, char const*, char const*, unsigned char, bool, char const*, bool) at .pio/libdeps/ddd-bt-rtl/PubSubClient/src/PubSubClient.cpp:761
  #1  0x400ddf8d:0x3ffcdaa0 in PubSubClient::connect(char const*, char const*, char const*, char const*, unsigned char, bool, char const*) at .pio/libdeps/ddd-bt-rtl/PubSubClient/src/PubSubClient.cpp:761
  #2  0x400d3108:0x3ffcdad0 in connectMQTT() at main/ZgatewayBT.ino:280
  #3  0x400dd7a8:0x3ffcdbd0 in loop() at main/ZgatewayBT.ino:280
  #4  0x400fd55d:0x3ffcdbf0 in loopTask(void*) at /Users/xxxxxx/.platformio/packages/framework-arduinoespressif32/cores/esp32/main.cpp:37
  #5  0x40090d3e:0x3ffcdc10 in vPortTaskWrapper at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/freertos/port.c:355 (discriminator 1)

[h2zero]

Ouch looks like something wasn't initialized and called nullptr. I'll look into this, thanks!

[h2zero]

@NorthernMan54 Please test #981 when you can and let me know if that fixes the issue.