B2OC: add a wrapper to check process argument

• Add a python wrapper to check the process argument is either hlt2 or spruce.
• Raise ConfigurationError instead of AssertionError.
• Apply the wrapper to some line builders in bbaryon_to_cbaryon_hh

To-do:

• Apply the wrapper to all line builder with assert inside. This should be done after !1035 (merged) is merged to avoid conflict.
• Remove all @configurable in line builders

Related to #282 (closed).

cc @abertoli