Detect architecture of GG device

[QuinnCiccoretti]

As I understand, the provisioner needs to know the architecture of the core it tries to provision because caches the appropriate greengrass binaries on your host machine. If this step is moved to template.sh.in in aws-greengrass-provisioner/src/main/resources/shell, you could use the output of arch to download the appropriate binaries on the device side, without the provisioner ever needing to know what architecture the device.

Of course, this may not be desirable in some cases, if the device has limited bandwidth or is restricted from downloading binaries from greengrass sites. In this case, you could have the detect-architecture as a default if there is no architecture specified, otherwise use cached binaries according to input.