Find common Qt5 dependencies once

CMakeLists.txt

@@ -156,6 +156,7 @@ if(ENABLE_WORKBENCH)
   if(Qt5_FOUND)
     message(STATUS "Found Qt ${Qt5_VERSION}: ${Qt5_DIR}")
   endif()
+  find_package(QScintillaQt5 REQUIRED)
   find_package(PyQt5 REQUIRED)
   find_package(SIP REQUIRED)
   separate_arguments(PYQT5_SIP_FLAGS)

qt/python/mantidqt/CMakeLists.txt

@@ -53,8 +53,6 @@ endif()
 
 # Wrapper module linked against Qt5
 if(ENABLE_WORKBENCH)
-  find_package(QScintillaQt5 REQUIRED)
-
   mtd_add_sip_module(MODULE_NAME _commonqt5
                      TARGET_NAME mantidqt_commonqt5
                      HEADER_DEPS

qt/widgets/common/CMakeLists.txt

@@ -845,10 +845,6 @@ if(ENABLE_WORKBENCH)
     endif()
   endif()
 
-  find_package(
-    QScintillaQt5
-    REQUIRED
-  )
 endif()
 
 mtd_add_qt_library(