Unconditional warning when optimizing all presets

After https://github.com/ankitects/anki/pull/4981, clicking "Optimize all presets" shows a warning that says "This will save any other changes you have made. Are you sure?" even if the user hasn't made any other change. This warning should be shown only if there are unsaved changes.

@Luc-Mcgrady

Start from the entry point for the “Optimize all presets” action and reproduce the warning with and without unsaved changes. Trace the existing unsaved-change state and add coverage wherever the relevant tests live; done means the warning appears only when other changes are unsaved.

Written by the indexing model from the issue text.