Register dynamic tracing options on tracing preference page

With this, tracing for EGit can be turned on under General > Tracing.

Bug: 371656
Change-Id: Id66fec8ec75f62b03ba5fe6cbee5f6ae50e1f474
Also-by: Curtis Windatt <cwindatt@ca.ibm.com>
Signed-off-by: Robin Stocker <robin@nibor.org>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Add tracing for selection handling

Trace output from user helps with investigating the problem on the
user's side.

Bug: 443449
Change-Id: I094c7da1a4ad39fb05b82e5456641bcf0c3591fb
Signed-off-by: Robin Stocker <robin@nibor.org>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>