Yocto/GL 3.3.0

This release marks the last release of the v3 line. It contains a few additions, mostly related to support libraries, as well as more example apps.
Starting from the next commit, incompatible changes will land in the main branch to begin working on the v4 line. The list of changes are:

• implemented command line apps with commands to reduce the number of demo apps (#1135, #1132, #1124, #1122, #1121)
• added a simple image viewer as a library component (#1134, #1133, #1123)
• added support for Json storage and IO in the new library Yocto/Json (#1131, #1130, #1129, #1128, #1127, #1126, #1116, #1112, #1111, #1110, #1109, #1108, #1107, #1105, #1102, #1098, #1102)
• mesh processing utilities (#1103, #1097, #1094, #1093, #1084, #1103, #1097)
• added STL and glTF IO (#1125, #1113, #1092, #1091)
• command-line parsing with JSON schemas (#1120, #1119, #1083)
• bug fixes (#1096, #1089)
• example sculpting app (#1087)
• city generation example (#1082)