Tests/RunCMake: Update cmake_minimum_required versions

For policy-specific tests, use the version before the policy was
introduced.  Otherwise, use 3.5 where possible.

Also, remove `cmake_minimum_required()` and `project()` calls from
individual cases where they are handled by `CMakeLists.txt`.

Tests/RunCMake/XcodeProject/XcodeIOSInstallCombinedPrune.cmake

@@ -1,6 +1,4 @@
-cmake_minimum_required(VERSION 3.3)
-
-project(XcodeIOSInstallCombinedPrune CXX)
+enable_language(CXX)
 
 if(XCODE_VERSION VERSION_GREATER_EQUAL 9)
   set(CMAKE_OSX_DEPLOYMENT_TARGET 10)