Separate helix-input and helix-graphics from helix-view.

[ryanabx]

This commit was split off from #14664

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This commit separates some primitives from helix-view into their own crates, for later use by crates that view might depend on, without causing cyclic dependencies.

I simply re-exported the stuff from helix-input and helix-graphics in helix-view, to avoid changing a lot of code.

For the maintainers: would something like this be acceptable? I opened this to discuss this change separately from my work-in-progress PR above, but the purpose of separating some of these files is to allow them to be used in a future helix-terminal-view crate so that we aren't bloating helix-view with the alacritty_terminal dependency.