Improve co-existence of usermods sharing I2C

Improve co-existence of several popular usermods with respect to shared I2C bus.
- ensure that i2c_sda and i2c_scl are used when defined
- ensure that HW_PIN_SDA / HW_PIN_SCL are not overwritten
- ensure that Wire.begin()nis always called with user-defined pins (remove rogue Wire.begin() without parameters)
- ensure that set.cpp / cfg.cpp use esp32-specific global Wire objects.

wled00/src/dependencies/time/DS1307RTC.h

@@ -14,7 +14,7 @@ class DS1307RTC
   // user-accessible "public" interface
   public:
     DS1307RTC() {}
-    static void begin() { Wire.begin(); }
+    static void begin() { /*Wire.begin();*/ }
     static time_t get();
     static bool set(time_t t);
     static bool read(tmElements_t &tm);