Arcyd: rename abdt_repoconfig -> abdt_repooptions

In anticipation of creating a new 'abdt_repoconfig', which will be used
for on-disk configuration of a repository, move the existing one out of
the way.

Test Plan:
$ ./precommit.sh
$ ./testbed/arcyd/acceptance_tests.sh
abdi_processargs: rename 'config' -> 'options'

Rename 'config' variables to 'options' so we can re-use config to mean
the on-disk 'hard' config.

Test Plan:
$ ./precommit.sh
$ ./testbed/arcyd/acceptance_tests.sh