Modify init function to return a Clock instance defined by a per-chip
SystemClock type and use this in macro setup
A proof of concept implementation for STM32 L0 chips.
This allows using embassy::main macros for STM32 devices that have the
clock setup logic.
This removes the need to duplicate the configuration for each individual
chip, but will instead pass on the configuration specified in the config
attribute.
Update nrf, stm32, rp macros with passing the config to a per-chip
configure function which assumes the appropriate configuration to be
passed to it.
To demonstrate this feature, the stm32l0xx clock setup and RTC is added which exposes
clock configuration different from stm32f4xx (and has a different set of timers and HAL APIs).
This allows crates depending on embassy that wants to use a different
module path to do so for the 'task' and 'main' macros, by passing the
parameter 'embassy_prefix'. The prefix defaults to '::', which will
retain the existing behavior.
