Add support for refund option on sendPrivateTransaction

[deiay]

What

As per flashbots docs, sendPrivateTransaction allows users to specify refund recipients. This exposes a refund parameter on the MevShareClient.sendTransaction and populates the json rpc request accordingly

Other small changes

Docs:

• Fix links to supported builders

Linting

• Add eslint lint config that enforces commas on types, inline with how types are linted in this repo. This make format on save work as one would expect
• Enforce consistent single quote in esconfig

[zeroXbrock]

thank you for the PR, @deiay! There are now some merge conflicts from some PRs that I just merged -- some overlap with smaller PRs. But the code you posted looks good. If you could please resolve the conflicts, I'll be happy to merge this.