Upgrade to iced 0.7

[carl-anders]

Only minor changes are needed to compile against iced 0.7.
I have tested all the programs in examples/ and they all compile, run and seem to work.
Updated iced_native to 0.8, iced_graphics to 0.6, iced_style to 0.6, iced to 0.7.

Examples time_picker and date_picker give deprecation warnings for chrono, but that is unrelated to the changes made.
There's some cargo fmt changes that should probably be done too, but I only applied formatting to code I changed in this PR.

[genusistimelord]

looks good thank you.

[carl-anders]

@genusistimelord If I do further changed to iced_aw, should I cargo fmt the files I changed or try to keep the old formatting where possible?

[genusistimelord]

yes we would appreciate that. cargo fmt is what we generally use.