Adds the option to define a client side load balancer.
There are only 2 available balancers by default: pick_first and round_robin. Default is pick_first.

This option can be defined on the client and passed as an option e.g.

. WithClientLoadBalancing("round_robin") // for default round robin instead of first value

fixes: #103

Note

This PR uses an old grpc deprecated option because some clients are not up to date to use the newest experimental api and therefore don't even have that option.

Linting fails because of ^

Error: runner/requester.go:326:23: SA1019: grpc.WithBalancerName is deprecated: use WithDefaultServiceConfig and WithDisableServiceConfig instead.  Will be removed in a future 1.x release.  (staticcheck)
		opts = append(opts, grpc.WithBalancerName(b.config.lbStrategy))
		                    ^
Error: Process completed with exit code 1.