The DAC driver defaults to enabling the channel trigger, but leaves it
at the default value of TIM6 TRGO, then performs a software trigger
after writing the new output value. We could change the trigger
selection to software trigger, but for this example it's simpler to just
disable the trigger.
It was only useful for doing #[embassy_executor::main(config = "config()")]`. Now that
it's gone, it makes more sense to build the config in main directly.
- Remove unused `MilliSeconds`, `MicroSeconds`, and `NanoSeconds` types
- Remove `Bps`, `KiloHertz`, and `MegaHertz` types that were only used
for converting to `Hertz`
- Replace all instances of `impl Into<Hertz>` with `Hertz`
- Add `hz`, `khz`, and `mhz` methods to `Hertz`, as well as
free function shortcuts
- Remove `U32Ext` extension trait
