select switch for switching profile & flightmode

- preprocessor defines allow to select the switch for choosing model
profile and flightmode.
choose one of:
- T5X_SW2_SELECTS_PROFILE
- T5X_SW3_SELECTS_PROFILE

choose one of:
- T5X_SW2_SELECTS_FLIGHTMODE
- T5X_SW3_SELECTS_FLIGHTMODE

- renamed
- TX_VOLT_PIN to T5X_TX_VOLT_PIN
- TX_BUZZER_PIN to T5X_TX_BUZZER_PIN
- TX_LED_PIN to T5X_TX_LED_PIN
to minimze risk of conflicts