Advanced keybinding combo support to exit vim insert mode regardless of layouts and without impacting typing

[eugenesvk]

When you need to exit Vim's insert mode, you either press Escape, which is a very inconvenient key, so you'd have to use some other OS trick to move it closer.
Or you use some sequence like jk, which is also bad because now you can't type jk literally, which is especially bad if you use another language where these physical keys represent a more common combination used in actual words.

A better solution would be to instead of having a "lazy sequence" like jk which breaks typing to use a sequence of movements that you'll never type using the same keys:

• hold j for 0.X seconds to exit (though this isn't instant, so not the best option)
• hold j and press+release k (while typing you'll release j before releasing k, so it's not a conflict). Think this is the least error-prone option
• "simultaneous" fast press and release of both j and k (in any order, timing is key here, should be user configurable). Will require effort to set a low enough threshold to avoid conflicts with typing

This is what advanced rebinding solutions like home row mods with QMK use. But then those require external apps, and those apps don't know what mode Zed is in, so you have a conflict with normal mode where you don't want the mode exit effect to be work, and then you'd need to write a plugin to signal mode changes to them, so it's complicated...

Also if this existed internally, you could use all the cool context combos implemented in Zed for interesting features like

• hold f and press j/k in Insert mode to move cursor down/up (for quick movements so you don't need to even change modes. Or you could even use it in non-modal editing)
• hold f and press j/k in Search field to go to next/previous match
• hold f and press j/k when top-level Menu is active to go donw/up in the menu list (and press a to activate the selected menu)
• to quickly toggle something off/on to see the different results (for example, za for code folding) you could hold z and press a then press a again without having to repeat the combo
• etc.