#1371 reorganized code to enable regression tests

For data I use a copy of arduinoPlugin (only the txtx files)
I won't check this is a	it is big and can be reproduced by sloeber
itself

Author: jantje

io.sloeber.core/META-INF/MANIFEST.MF

@@ -30,7 +30,7 @@ Require-Bundle: org.eclipse.cdt.managedbuilder.core,
 Export-Package: cc.arduino.packages;x-internal:=true,
  cc.arduino.packages.discoverers;x-internal:=true,
  cc.arduino.packages.ssh;x-internal:=true,
- io.sloeber.core;x-internal:=true,
+ io.sloeber.core;x-friends:="io.sloeber.tests",
  io.sloeber.core.api,
  io.sloeber.core.builder;x-internal:=true,
  io.sloeber.core.common;x-friends:="io.sloeber.tests",