[UART] add sendBreak(duration) API

[sandeepmistry]

Note: SERCOM_USART_CTRLA_FORM needs to be set to auto baud to enable break detection.

Since there is no easy way on the SAMD to detect the break duration, the break value is set to 0xffff when a break is detected, otherwise -1 when no break is detected.

[ArduinoBot]

✅ Build completed.

⬇️ Build URL: http://downloads.arduino.cc/PR/samd/package_samd-b191_index.json

ℹ️ To test this build:

1. Open the Preferences of the Arduino IDE.
2. Add the Build URL above in the Additional Boards Manager URLs field, and click OK.
3. Open the Boards Manager (menu Tools->Board->Board Manager...)
4. Install Arduino SAMD core - Pull Request [UART] add sendBreak(duration) API #329
5. Select one of the boards under SAMD Pull Request [UART] add sendBreak(duration) API #329 in Tools->Board menu
6. Compile/Upload as usual

[ArduinoBot]

✅ Build completed.

⬇️ Build URL: http://downloads.arduino.cc/PR/samd/package_samd-b192_index.json

ℹ️ To test this build:

1. Open the Preferences of the Arduino IDE.
2. Add the Build URL above in the Additional Boards Manager URLs field, and click OK.
3. Open the Boards Manager (menu Tools->Board->Board Manager...)
4. Install Arduino SAMD core - Pull Request [UART] add sendBreak(duration) API #329
5. Select one of the boards under SAMD Pull Request [UART] add sendBreak(duration) API #329 in Tools->Board menu
6. Compile/Upload as usual

[sandeepmistry]

Closing this for now, we can do something outside the core for now.