Fix: Isolate SBOM PATH flag

Fix: Isolate SBOM PATH flag

SBOM's path flag does not work as expected. We need to introduce a new
flag called SBOM_PATH to isolate the path where SBOM is going to be
extracted to and executed from. By default this is set to $WORKSPACE but
some projects need to execute the sbom from a different location in their
code. See https://github.com/opensbom-generator/spdx-sbom-generator/issues/227

Issue: RELENG-4213
Signed-off-by: Jessica Wagantall <jwagantall@linuxfoundation.org>
Change-Id: Ibaaf4f89035f8aa9a773e199cf0cacb6c1e14947