[BOLT][CMake] Redo the build and install targets

The existing BOLT install targets are broken on Windows becase they
don't properly handle the output extension. We cannot use the existing
LLVM macros since those make assumptions that don't hold for BOLT. This
change instead implements custom macros following the approach used by
Clang and LLD.

Differential Revision: https://reviews.llvm.org/D151595