Revert "File Search Result Name was never correctly converted from OS encoding to UTF-8"

This reverts commit 85682e5586a60487d8aa65564dc0a77c24f080d4.

The reason is because the fpgFindFirst and fpgFindNext functions already fix
the sr.Name encoding. So doing it in the base filelist class corrupts the
text because the encoding is applied twice. Amazing nobody picked this up
for so long.
textedit: SaveToFile() and LoadFromFile() now does OS Encoding calls.

The AFileName parameter is of type TfpgString (thus UTF-8), and we need
to ensure that it is the same encoding as the underlying file system
before we can save or load files.
nanoedit: use the textedit's Save and Load file methods

This then automatically handles cursor positions, scrollbars, invalidate
etc.
GDI: Correctly define visibility for methods in TfpgGDIFileList