Truffle/API test:  additional documentation on the new instrumentation tests; move into project with other tests and add an entry in package-info.java

--HG--
rename : graal/com.oracle.truffle.api.test/src/com/oracle/truffle/api/test/instrument/WrapperTest.java => graal/com.oracle.truffle.api.test/src/com/oracle/truffle/api/test/InstrumentationTest.java
SL/instrumentation:  minor cleanups in sl.test.instrument
Merge with db2ac421649a00f0f8e1022d9daa682a0e9dd114
set protection domain to null for classes loaded by the Graal class loader
put some security sensitive actions into a privileged action
Fixed compile error in os_windows.cpp.
Truffle-DSL: fixed uninitialized triggered a deopt even if fallback was set to true.