build_llvm_release.bat: add tarball export to x64 release (#79840)

Like linux releases, export a tar.xz files containing most llvm tools,
including non toolchain utilities, llvm-config, llvm-link and others.

We do this by reconfiguring cmake one last time at the last step,
running the install target so we do not need to recompile anything.

Fix #51192
Fix #53052