Could from_slice_unchecked be made const for the string types?

[ModProg]

This would allow putting them in constants.

The only issue I foresee would be the plan to eventually move away from zero terminated strings, as mentioned here:

dbus-rs/dbus/src/strings.rs

Lines 64 to 72 in d6f5305

	/// View this struct as a CStr.
	///
	/// Note: As of dbus 0.9, this is made private to be able to make it easier for a potential
	/// native implementation using "str" instead of "cstr".
	pub (crate) fn as_cstr(&self) -> &CStr {
	unsafe {
	CStr::from_bytes_with_nul_unchecked(self.0.as_bytes())
	}
	}

Code change required for this would only be a single line, so this is more about the question of whether this should be implemented. As I'd be happy to contribute the needed PR.