Add unstable_offset_of feature to use the unstable offset_of macro

[est31]

Add a cargo feature unstable_offset_of to use the unstable core::mem::offset_of!() macro (rust-lang/rust#106655). This allows for unsized structs (#25) and many other things. It also helps with testing of the upstream offset_of macro: testing is now as easy as enabling this feature, one doesn't have to change the usages from memoffset::offset_of to core::mem::offset_of.

[Gilnaa]

Thank you very much.
Will try to remember to publish it to crates.io tonight

[est31]

Thanks @Gilnaa for the fast review! ❤️

[Gilnaa]

Failed to remember that night :)
Anyway, published as v0.9.0, thanks again and have a nice weekend.

[est31]

@Gilnaa thanks for having done the release!