Investigate Bob skipping swaps

[lalexgap]

Currently SAFE V2 does not provide a way for Bob to skip swaps he doesn't want to commit to.

It might make the protocol easier to use and rule out some [edge cases] (https://www.notion.so/statechannels/HTLC-free-SAFE-e999aafe604c4ce3bc69aec1000971b0#d77f5774dd6b4aeaa05c824854ec48c2) if Bob can skip swaps.

[lalexgap]

The consensus is that this is not immediately important. (see https://www.notion.so/statechannels/HTLC-free-SAFE-e999aafe604c4ce3bc69aec1000971b0#d77f5774dd6b4aeaa05c824854ec48c2)