Implement UART type erasure

[bugadani]

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[bugadani]

Since 1.81 fat LTO dislikes something and miscompiles this... for C6 only for some weird reason. Nevermind a different test is broken with thin LTO...

[bjoernQ]

Not really related but ....

I wonder if we should doc-hide all those Instance/RegisterAccess traits 🤔

We do for some peripherals (e.g. I2c) but for most we don't - however it's something that would be just confusing to users in best case

[bugadani]

In the long run, I want to split out the RegisterBlock/signal part of the trait, and make it public. The rest (i.e. the actual driver implementations) will I think remain private. I'm hiding these things mostly as an "under construction" sign.

[bjoernQ]

LGTM - feel free to think about doc-hiding the Instance trait or merge as is

[bugadani]

Are we fine with me disabling LTO in the test suite?

[bjoernQ]

Are we fine with me disabling LTO in the test suite?

What would be the alternative?

[bugadani]

Figuring out what's wrong, fixing the compiler and holding off the PR until the fix is released 😅