Fix #80361

Fix #80455

* new reg service and always on mnemonics

* missed one

* use new node module and accessibility service

* add typings

* adopt accessibility service

* make it lazy

part of strict null work

Calling `fire` with zero arguments results in the emitter firing with `undefined`. This is often not expected or desired. It should be explicit that the emitter is fired with undefined

Issue #62952: Disabled clear button only when all fields are cleared and enabled clear button after any input in search form.

In these cases, the programmer has explicitly indicated that the type should be nullable

Fix #52590 - don't move focus when clicking the search details buttons with screenreader mode turned on.
Because NVDA sends click events instead of key events when pressing space.
Also update this dynamically for the search option buttons

Fix #52274 - don't move focus when clicking the find option buttons with screenreader mode turned on, because NVDA sends click events instead of key events when pressing space on a focused button

Added find options checkboxes to terminal find widget with keybindings and hooked the buttons up to use the new xterm.js find api.

Fixes #58826