This reverts commit b08610bc3e.
The check for LLDB build variant really needs to happen in
build-script-impl. build-script can still take options after
the '--' separator that may control the final determination
of the LLDB build variant. These weren't all being considered
by the logic in build-script.
The configuration script for Foundation respects debug and release builds so a new option for foundation-build-type has been added to control the build variant of Foundation.
Resolve the FIXME for adding a mechanism for a custom invocation of running the Foundation unit tests
Foundation now has an install target provided from the generated ninja script such that the potentially error prone install script is dramatically simplified into a single encapsulation of a ninja phony target of "install"; so adopt this new target for installation
