Add missing include files

The problem with missing include files only becomes obvious after clang-format
changed the order of the include statements.

core/data/test/trd/compareTrdDigi.h

 #ifndef COMPARETRDDIGI_H
 #define COMPARETRDDIGI_H 1
 
+#include "gtest/gtest.h"
+
 void compareTrdDigiDataMembers(CbmTrdDigi& test, Int_t padChNr, ECbmModuleId systemid, ULong64_t time, Double_t charge)
 {
   Int_t retValInt {-222};

core/data/test/trd/compareTrdHit.h

@@ -2,7 +2,7 @@
 #define COMPARETRDHIT_H 1
 
 #include "comparePixelHit.h"
-
+#include "gtest/gtest.h"
 
 void compareTrdHitDataMembers(CbmTrdHit& test, HitType type, Double_t z, Double_t dz, Int_t refid, Int_t address,
                               CbmMatch* match, Double_t time, Double_t errortime, Double_t x, Double_t dx, Double_t y,

core/data/test/trd/compareTrdPoint.h

@@ -2,6 +2,7 @@
 #define COMPARETRDPOINT_H 1
 
 #include "compareFairMCPoint.h"
+#include "gtest/gtest.h"
 
 void compareTrdPointDataMembers(CbmTrdPoint& test, Int_t trackID, Int_t detID, TVector3 posin, TVector3 momin,
                                 TVector3 posout, TVector3 momout, Double_t tof, Double_t length, Double_t eLoss,