Make sure all embedded-hal interfaces can implicitly copy

[jamesmunns]

For compat reasons, we should support implicit copy (if the user passes in a slice from .text) of chunks on all interfaces. We currently do this for UARTE, but not for SPIM/TWIM.

[kalkyl]

Instead of returning Error::DMABufferNotInDataMemory?

[Yatekii]

I think the majority vote was in favor of returning an Error on the main interface but providing a call which does implicit copy if you ask it to.
But the interfaces should all have the same behavior/look :)

[jamesmunns]

The goal was:

1. When using embedded-hal traits, implicitly copy if necessary (when we would otherwise return DMABufferNotInDataMemory)
2. When using nrf-hal direct interfaces, do not implicitly copy, instead return the error

This is because some (non nrf specific) drivers send constant strings, which will end up in .text.

[kalkyl]

Oups, i messed up my first PR and accidently pushed the wrong branch, still getting used to the workflow of contributing, haha! Anyways, i now submitted the one i was supposted to (PR #164) for spim transfer :)

[kalkyl]

Added Twim write/write_read aswell and made a new PR #165 with both Spim and Twim instead, sorry for the PR mess, i'm new here... :)

(Not sure why the githud build failed (##[error]Process completed with exit code 1), is that a common issue or is it me? It builds just fine on my machine...)