Watch files for changes and reload them

# Description
I often edit files and then run linter/formatter in other terminal tab. Some editors automatically reload files from disk on changes, while others provide keybinding to do this. So, I want to see this functionality in Edit.
# Possible solutions
1. Automatically reload files on external changes
2. Provide actions for this:
- Add `File -> Reload From Disk` action and (maybe) keybinding
- Add `File -> Reload All From Disk` action and (maybe) keybinding

Many editors use CTRL-R keybinding to reload files. I don't know which keybindings we can use since CTRL-R is already used for `Replace` and CTRL-SHIFT-R also calls it (#218).

The issue names no files, tests, or entry points. Start by locating the editor's file-loading and keybinding handling, then determine whether the intended behavior is automatic reload, reload actions, or both. Done means the selected reload behavior is implemented without conflicting with the existing Replace shortcuts and is covered by relevant tests.

Written by the indexing model from the issue text.