tmf: Move the tmftracetype extension point to tmf.core

tmf: Move the tmftracetype extension point to tmf.core

Split the current "tmf.ui.tracetype" extension point into a
tmf.core.tracetype and tmf.ui.tracetypeui. "tracetypeui" refers to
the ID of the "tracetype", to add UI elements like type-specific icon
and events editor.

This separation makes it possible to unit-test the trace validation
without depending on UI/SWTBot tests. We will also eventually be able
to handle trace opening/validation in completely headless mode.

Change-Id: I227a199d1dddf62ad07b60392793b4694d0ec2de
Signed-off-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Reviewed-on: https://git.eclipse.org/r/21421
Tested-by: Hudson CI
Reviewed-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
IP-Clean: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Tested-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>