clang-format vsix cmake build: use ${LLVM_TOOLS_BINARY_DIR}/${CMAKE_CFG_INTDIR}

as the location for grabbing clang-format.exe, and also output the .vsix here.

This allows us to find clang-format.exe when building from a MSVC Solution.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@196512 91177308-0d34-0410-b5e6-96231b3b80d8