Based on the HAL from stm32wl, the peripheral driver has been
modified to fit into embassy, using the embassy APIs, providing
operation of the radio peripheral.
The initial version does not offer any async APIs, but the example
shows how the radio IRQ can be used to perform async TX of the radio.
* Generate a core index put into the PAC for the peripherals to use as
index into registers.
* Add EXTI v2 which uses CORE_INDEX to index exti registers
