CppTools: Move QtVersion and BuildTargetType

QtVersion to utils/cpplanguage_details.h which already contains similar
flags.

BuildTargetType to ProjectExplorer, next to BuildTargetInfo (but not in the
same header to not pull that in everywhere).

Removes dependency on ProjectPart from RawProjectPart.

Change-Id: I5791065e4266f20c2657ee4b1b594df04b238a1c
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

src/libs/utils/cpplanguage_details.h

@@ -72,4 +72,6 @@ constexpr bool operator&&(LanguageExtension first, LanguageExtension second)
     return static_cast<unsigned char>(first) & static_cast<unsigned char>(second);
 }
 
+enum class QtVersion { Unknown = -1, None, Qt4, Qt5 };
+
 } // namespace Utils