Add support for LBRY Credits

[shrnkld]

To do:

Dev:

• [ ] support for LBRy on Cloudchains back-end infra
• [ ] add LBRY to XLite configs

UI:

• [x] prepare LBRY asset icon
• [x] prepare LBRY info links

QA:

• [ ] test XLite LBRY tx's and UI

[shrnkld]

Info link: https://lbry.com Explorer: https://explorer.lbry.com Icon assets:

[kodxana]

explorer.lbry.com :)