[EPIC] Include a relayer implementation in e2e tests

[srdtrk]

Right now, all e2e tests pass using manual relaying. It is worth looking into a path for relayer integration. Since union's voyager relayer already has similar functionalities, it might be worth developing plugins for it.

• Use voyager to update client (on eth)
• Use voyager to relay timeouts (on eth)
• Use voyager to relay recv packet (on eth)
• Use voyager to relay ack packet (on eth)

[srdtrk]

Work on this is taking place in voyager-eureka-modules at the moment. If it reaches a satisfactory status, then it can be merged into this repo.

While trying to implement the relayer, I noticed a missing feature, that is multicalls. Which is the ability to include multiple contract calls in a single transaction. This was added in #87 to this repo. Doing this also opened up another major gas optimization using transient store, which is being merged in #91.

[srdtrk]

This issue is closed in favor of #121