feat(android): folder and 2FA secret can be changed, and the buttons wear icons

The folder had no row of its own - it shared "Folder / tags" with the tags,
so neither could be touched. It is now CHOSEN from the known folders rather
than typed: a typo would file the entry under a folder nothing displays,
here or on the desktop, and it would look lost. Tags stay read-only because
they are an array in the snapshot, and writing one as a string would break
its shape for the desktop.

The 2FA secret gets its own masked row. The code has had a panel for a long
time, but it is computed and renewed every thirty seconds; the secret is what
one sets, changes and removes, and nothing allowed that from the phone.

User, Pass, Copy, Show and Edit become drawings. Four words on a list row left
little room for the entry's name and had to be re-read every time. Every icon
carries an aria-label: replacing a word with a drawing must not take the
information away from someone listening to a screen reader.

mainApk.pas

@@ -1016,7 +1016,8 @@ begin
   // des pieces jointes et des horodatages, que PatchEntryField ecraserait sans
   // rien y comprendre.
   if (AField <> 'title') and (AField <> 'site')
-     and (AField <> 'username') and (AField <> 'password') then
+     and (AField <> 'username') and (AField <> 'password')
+     and (AField <> 'folder') and (AField <> 'totp_secret') then
   begin
     RefuseChange('That field cannot be changed from here');
     Exit;