HAL_QURT: revived QURT HAL

[tridge]

This is a revival of the old QURT HAL for the new ModalAI boards This does not build yet. Issues:

• what mutex type to use?
• string functions missing, like strnlen()
• doesn't yet build ARM frontend app

Testing:

• use ./waf configure --board QURT
• build: ./waf --target examples/UART_test