add the support for displays without a RST pin

[pyaillet]

The choice was made here to rely on an internal NoPin implementation to hide the details and expose it as an Alias type.

Proposal fix for #3

It would be used like this :

let display = DisplayNoRST::st7789_without_rst(di);

And it would be defined as:

  pub struct Twatch<'a> {
      pmu: Pmu<'a>,
      display: DisplayNoRST<EspSpi2InterfaceNoCS, mipidsi::models::ST7789>,
      [...]
  }

[pyaillet]

Many thanks for the review :)

I removed the init seq from this PR and most of the comments shoulds be resolved now.