Improve goto_word experience

[shybovycha]

The goto_word behaviour is not everyone's cup of tea - it changes the text, making it harder to figure out where user wants to jump and it does not allow to narrow down the jump labels - it always shows labels for every word.

In the land of neovim, there are few plugins with a similar approach, but unlike goto_word, those allow user to narrow down the labels by providing prefix search and they are not as obstructive - like leap.nvim or flash.nvim.

I was wondering if it makes sense to provide a similar functionality in Helix. So I went ahead and made a proof-of-concept PR. It works with movements and in selection mode and allows to specify a prefix for search. It is introduced as a new function, flash so it does not interfere with the existing goto_word behaviour.

Screen.Recording.2025-10-23.at.5.54.09.pm.1.webm

Would greatly appreciate feedback on this!