Consolidate primary rule assignments

[codefromthecrypt]

Like this, except for primary rules. This implies care in type checking before returning a corresponding primary sampler.

    .putSecondaryHttpRule("gateway", "gatewayplay",
      pathStartsWith("/play"), RateLimitingSampler.create(50)
    )
    .putSecondaryRule("playback", "gatewayplay",
      passive()
    )
    .putSecondaryRpcRule("auth", "authcache",
      methodEquals("GetToken"), RateLimitingSampler.create(100), 1 /* TTL */
    );

[codefromthecrypt]

NOTE: it will look similar but not be exact as primary doesn't support things like TTL or "active/passive" concepts... mainly about the rule declaration part.. first two parameters (matcher, sampler)