Prettify abi-gen

[xianny]

Expected Behavior

prettier should be run as part of abi-gen. We are currently checking in generated-wrappers so that we can compare diffs when reviewing. Prettifying will minimise the amount of whitespace/formatting diffs and make reviews easier, and should be enforced immediately after generating wrappers.

Current Behavior

prettier must be run when building/as part of build scripts. We're doing extensive work on abi-gen right now and run into whitespace conflicts, huge unnecessary diffs, etc.

Possible Solution

Implement prettier within the abi-gen code generation script.

[feuGeneA]

Just one more quick note on motivation. As much as possible, we should be generating not just working code, but good code. It's not hard to use prettier within a run of abi-gen, so we should!