Type erase SpiDma once created

[MabezDev]

It is currently impossible to declare SpiDma as a type because of its use of private types.

pub type SpiType<'d> = SpiDma<'d, esp32c3_hal::peripherals::SPI2, esp32c3_hal::dma::private::ChannelTx<'d, gdma::private::Channel0TxImpl, gdma::private::Channel0>, esp32c3_hal::dma::private::ChannelRx<'d, gdma::private::Channel0RxImpl, gdma::private::Channel0>, gdma::private::SuitablePeripheral0>;

The easy option is to make these modules public and then seal the traits etc, but it would be better in general if we could completely erase this type information once we've satisfied the trait bounds. Any ideas on how to go about this @bjoernQ?

This is somewhat blocking async SPI as its impossible to pass the spi struct into a embassy task.

[bjoernQ]

Having a way to erase the types would be very convenient - probably also for other use-cases - but sounds like a lot of work.
I guess to unblock your work on async-SPI it's fine to go the easy way for now and later we can still add a way to erase the types

[bugadani]

"Closes" directives don't work in comments, so you guys should probably close this :)