Custom keys manager

[Jasonvdb]

Outputs from channel closes now get spent directly to on chain wallet.

• Extends the default LDK keys manager so we can provide our own signer provider and overrides functions that return destination script and shutdown script pubkey.
• Existing sweeping logic is kept for channels opened prior to this update. Going forward as a new channel is opened the channel ID is appended to a file so when it comes time to sweep outputs from a channel close it will skip this sweeping step if the channel ID is found as the channel was opened with new adapted keys manager.
• getAddress() in JS needs to be adapted to return witness program and program version. Example app shows how.

[coreyphillips]

Created PR here to move the witness program logic to lightning-manager.ts so future devs implementing the library don't need to worry about performing that logic in getAddress. Also checks for taproot addresses to set the witnessProgramVersion accordingly.