Rust macros and types cleanup

[matejcik]

building on top of #3938 for the dbg_print! macros

• use Rust's built-in CStr in favor of a stand-alone crate
• make use of c"" string literals in favor of cstr! macro
• introduce uformat! convenience macro that will return (by default) a ShortString with the formatting result.
  • unwraps internally because otherwise we just write unwrap!(uformat!()) everywhere, that's pure noise.
  • if you want to handle errors, create a String instance and invoke uwrite! on it manually
• unify all code to use a ShortString instead of picking a size ad hoc and carrying multiple copies of String<N>
  • this saves a meager ~1 kB of flash
• centralize #[macro_use] to exactly one place (the macros module in root). Import all other macros as needed (so things like obj_type! are explicitly imported from micropython::macros. Seems just plain nicer.)
• extend dbg_print!() functionality to places that don't have micropython, such as bootloader-emu (but note that you have to enable the debug feature)

[github-actions]

core UI changes	device test	click test	persistence test
T2T1 Model T	test(screens) main(screens)	test(screens) main(screens)	test(screens) main(screens)
T2B1 Safe 3	test(screens) main(screens)	test(screens) main(screens)	2724
T3T1	test(screens) main(screens)	test(screens) main(screens)	test(screens) main(screens)
All	main(screens)

[obrusvit]

Feel free to include #3953

[obrusvit]

Do you think we could achieve formatting translated template strings with uformat!?
Something like this would be desirable:

let text = TR::reset__select_word_x_of_y_template.map_translated(|s| {
    uformat!(s, n_choice, n_words)
});

ufmt complains with error: expected string literal

[matejcik]

Do you think we could achieve formatting translated template strings with uformat!?
Something like this would be desirable:

we can't because the format literals are parsed at compile-time.
we will need to find another library, or write our own

[matejcik]

Feel free to include #3953

very nice, cherry-picked as d0d6780

[mmilata]

nice cleanup