Add x-address v1.0 support, adding networkID

[WietseWind]

Todo/suggestion:

• Extend xls5 (x-addresses) to support network id.
• Sets the MSB on the flags (0x80) to indicate the final 4 bytes are network id.
• Then tag and no tag still work, but 64bit tag is invalid

Addresses could have a new life disambiguating exchange addresses across multiple networks as well as multiple dest tags

Updated proposal (XLS5.1 instead of XLS5):

• 0005 XLS-5.1d NetworkID extension to X-Addresses XRPL-Standards#142

Reference implementation:

• https://www.npmjs.com/package/xrpl-tagged-address-codec

Sample:

• https://jsfiddle.net/WietseWind/05rpvbag/

We're actively going to push for this together with exchanges.

[mvadari]

I'm not part of the day-to-day management of this repo, but I'll respond since I was assigned.

I don't think the team has the capacity to implement this in the near term, but feel free to open a PR 🙂