Add keyboard shortcut for "Clear cache and reload"

I'm in a lot of rooms and with bans and redactions happening, quite often (multiple times per day) you have to do a "Clear cache and reload" to get the message list updated properly.

Unfortunately "Clear cache and reload" is buried deep in the settings, on element-web it takes three (3) mouse clicks + scrolling down a page + another mouse click.

Please add a keyboard shortcut for this function. Or really any other way to get to this button fast. :)

Start by locating the existing “Clear cache and reload” action in the settings UI and the code handling keyboard shortcuts. Check how other shortcuts are registered, then verify that the new shortcut reliably triggers the same action and remains discoverable or avoids conflicts.

Written by the indexing model from the issue text.