Add hard coded variables for registration into client conf

[mingyech]

Currently, the client hard codes some variables in the registrars. Consider putting them in their respective protobuf messages in client conf.

variable	current assignment	usage
connection delay	api bdapi dns bddns decoy	Length of time (in ms) to delay after confirming successful registration before attempting a connection, allowing for propagation throughout the stations. The decoy registrar uses a interval to randomly select a value configured with min max, so we may need to two values for it.
maximum registration attempts	api bdapi dns bddns	Maximum registration attempts before giving up. Currently, api and bdapi keep maximum registration retries, whereas dns and bddns keep total attempts. Lets change one of them to match the other.
reg width	decoy	Number of decoy registrations to send simultaneously.