Bump version to 4.2.3-dev
Update copyright for 2021
Bug 570025: [RJ-Dbg] Fix update of TracepointManager.isAnyEnabledBackport-of: 86e982f999ad97c2bda762beeb5c28c877f95466Change-Id: I678b55f388dba008e2965f10a3ed2458dd5bbed7