Refactor to pass nextConfig down from the top level

[lindsaylevine]

this issue really began in next 10.0.2 when the framework changed loadConfig to be async. prior to 10.0.2, we had a sync getNextConfig helper that could be imported and called anywhere with ease. we had a huge refactor ahead of the autoinstall release that turned our entire source async, just to accommodate this change. now, after a lot of thinking and hard work from @rayriffy via #178, our hope/plan is to refactor our codebase to pass nextConfig down from the top level, instead of importing everywhere and making everything async.

per @rayriffy's PR and original issue (#115), we should (through this work) support looking for the config file in the publish dir if it doesn't exist at the root. this would support @rayriffy's use case and other monorepo setups.