Clear selection when exiting visual mode

[thomasschafer]

After exiting visual mode with Escape, the selection is currently not cleared until another action is performed such as moving the cursor left or right. This PR fixes that, clearing the selection as soon as Escape is pressed to match the behaviour of Vim.

[132ikl]

mentioned this in the Discord, but wanted to add it here also that #867 also implements this, so assuming we get that merged in a timely fashion we can close this PR in favor of #867. otherwise, we can merge this before next Nushell release.

[sholderbach]

Ah making that part of the Esc handler itself is elegant. Should also transfer to the emacs style bindings.

If you want to revisit that part of #867 feel free to update the changes from it, otherwise this is closed by it.