Test: backup and hot-exit

[bpasero]

Refs: #84672

• windows@RMacfarlane
• macOS @JacksonKearl

Complexity: 3

This milestone, backup / hot-exit was rewritten to work with custom editors. This test plan item is to verify there are no regressions for existing text based editors.

Steps:

• work with dirty files and dirty untitled editors
• with default settings you should be able to quit VSCode (File > Exit) without getting asked to save and all dirty content is restored after next startup
• turn hot exit off in settings and verify that quitting now will ask you to save/revert/cancel for each file or untitled editor
• verify each of save/revert/cancel works as expected and you can close VSCode (unless you picked "Cancel")
• verify that you can kill VSCode (literally the process) with dirty files and upon restart your content is still preserved (we backup after 1s delay after making content changes)

[RMacfarlane]

Works great!