Miscellaneous fixes and improvements

[chris-durand]

• Fix Rcc::enable for STM32H7 comparator
• Add STM32 advanced timer isOutputEnabled()
• Suppress GCC ABI nuisance warning ("note: parameter passing for argument of type
  '...' when C++17 is enabled changed to match C++14 in GCC 10.1")
• Fix RTT logger if data structure is not in RAM with lowest address
• Allow unit test case names in snake_case (test_foo())
• Treat missing return in function as error (this is always undefined behaviour)
• Fix compilation of STM32G0 DMA. The CI didn't catch it because the template function is never instantiated in the test suite.
• Fix reconfiguring DMAMUX requests
• Fix STM32H7 32-bit timer counter size
• Fix STM32H7 ADC asynchronous clock
• Fix sampling time configuration in STM32F3 ADC driver
• Fix compilation of STM32 DMA channel clearInterruptFlags()

[salkinium]

Thanks!