Fix land cover import class definition screen

[azvoleff]

• [x] reset button pulls up the full ESA class list (it should pull up correct codes for what is actually in the file)
• [x] save/reload of the definitions isn't working

@gdaldegan - can you expand if you notice any further issues with that screen?

[gdaldegan]

Import LC raster dataset functions are working great

• reset button is working fine, pulling the 7 UNCCD land cover classes.
• save/reload lc definitions are working fine.

[gdaldegan]

import LC vector (SHP) dataset returns the following error for the 'Edit definition' button:

[azvoleff]

@gdaldegan - do you still see this (whenever you get on the latest version)?

[gdaldegan]

just installed the latest exp. version on QGIS 3.22 and got the same message