walletkit: add startHeight parameter to ListSweeps and ListSweepsVerbose

[bhandras]

Pull Request Checklist

• PR is opened against correct version branch.
• Version compatibility matrix in the README and minimal required version
  in lnd_services.go are updated.
• Update macaroon_recipes.go if your PR adds a new method that is called
  differently than the RPC method it invokes.

[guggero]

Code looks good but need to bump the minimum version requirement as it won't be backward compatible (or fail with weird side effects because the new parameter is just ignored by old versions).