refactor: Set string properties use g_set_str()

String properties can use g_set_str to reduce redundancy.

This commit replace all g_strcmp0 like string property setting with new gnome api g_set_str.

Close #1892 (closed)

I checked, with these regexes

• g_strcmp0\s*\(.*->.*!=
• ide_str_equal0\s*\(.*->.*
• ide_set_string