Remove ViewArgument

[flosse]

Motivated by #1638 (comment) this PR basically reverts #1444.

[flosse]

@PoignardAzur and @Philipp-M as announced, here is a PR that removes the ViewArgument trait.
@DJMcNab You had good reasons for introducing the trait, so there are certainly reasons to keep it.
I don't want to destroy your work, but if you're okay with reversing this step, it would be a bit of a relief in a few places (at least until rust-lang/rust#107374 is stabilized).

[PoignardAzur]

Really appreciate that you took the time to do that refactor!

We haven't had a big discussion about whether we want to remove ViewArgument, but as your PR shows, we're not using it anyway, and Xilem doesn't really have any maintainers right now, so I'll make a judgment call and say we can merge this without delay.

[flosse]

There were changes on the main branch in between... I'll fix that in a minute.

[RagibHasin]

I'm a little too late to the party it seems. I have just been using this feature to ease on unwrapping in handlers.

I guess it is refactor time for me. 😢

[flosse]

I'm a little too late to the party it seems. I have just been using this feature to ease on unwrapping in handlers.

What exactly do you mean by that?
Can you give an example of what had improved with ViewArgument and what is now gone?