Warn users when changing format or renaming into hidden file

[marcoambrosini]

We should warn users when they're changing the format or adding a dot at the beginning of the filename upon renaming.

@tobiasKaminsky and @sorbaugh, the implementation of this should be fairly straightforward, we a confirm/cancel dialog with cancel as primary action. Let's make sure the wording is the same on all platforms.

Here's a proposal:

Case 1: renaming into .dotfile
Important: we only want to show this warning if hidden files are actually hidden
Text: Adding a "." at the beginning of the file name could result in the hiding of the file. The file can be shown again by activating the "Show hidden files" option in the files settings.
Checkbox: Do not show this warning again

Case 2: renaming the file extension
Text: Changing the file extension may render the file unusable.
Checkbox: Do not show this warning again

We need to store these in the files settings. For these I would create a new settings sections named "Warnings".

[szaimen]

There is already a PR that does this: #43366

[tobiasKaminsky]

All other warning on Android are inline the dialog:

So I chose to do it similar.