Service weights should also apply to connect mesh

#### Feature Description

When registering services (as per https://www.consul.io/docs/discovery/services#dns-srv-weights ) you are allowed to set service weights so clients can use them to balance the requests accurately to the destination capacity. Weights work fine when using consul DNS interface but not when using connect mesh as consul register the sidecar proxies with default weight values of 1 and 1 (for passing and warning).

#### Use Case(s)

As described in this forum post https://discuss.hashicorp.com/t/weighted-round-robin-with-consul-connect/18526 when your upstream servers are not of the same size (using AWS spot instances for example) and you have different number of CPU/RAM/Network resources, it would be great to allow sidecar proxies to also use the weights.