Refactoring neutron agent linux and ovsdb config opts
to be in neutron/conf/agent so that all the config options
reside in a centralized location. This simplifies the
process of looking up the config opts and provides an easy
way to import.
NeutronLibImpact
Change-Id: Ib1e0e63dec2985c417412d1ecc68e2a74ef87182
Partial-Bug: #1563069