Check availability of required programs before execution
Check availability of required programs before execution

Add a simple check to crtSignedContainer.sh to make sure basic tools, openssl
commands, and other signtool and signframework executables are found in PATH,
before proceeding.

Signed-off-by: Dave Heller <dadf76b92c028da3488e57973c6c8cd3d5ab990c@linux.vnet.ibm.com>

hellerda/sb-signing-utils,hellerda/sb-signing-utils