Fix OpenTherm conflicting symbols

[barbudor]

Description:

Following discussion on Discord it appears that OpenTherm and NimBLE are conflicting on a few symbols like READ and WRITE
So I prepended OPTH_ on every symbols just to be safe

Checklist:

• The pull request is done against the latest development branch
• Only relevant files were touched
• Only one feature/fix was added per PR and the code change compiles without warnings
• The code change is tested and works with Tasmota core ESP8266 V.2.7.4.9
• The code change is tested and works with Tasmota core ESP32 V.1.0.7.4
• I accept the CLA.

NOTE: The code change must pass CI tests. Your PR cannot be merged unless tests pass