feat: Upgrade to parachain 0.7.x

[daniel-savu]

• Changes lots of denominations from Satoshi/Planck to BTC/DOT respectively. Please pay extra attention that I didn't break anything when reviewing
• Depends on https://github.com/interlay/polkabtc-js/pull/286
• Considers a relayer registered if stake > 0
• Replace request is no longer Accepted/Pending but Pending/Completed/Cancelled
• Adds several @polkadot dependencies. Different versions were installed by polkabtc-js and polkabtc-stats and type conflicts would appear due to lack of a default explicit package. I'll try to remove these once I can test https://github.com/interlay/polkabtc-js/pull/286

[nud3l]

Note: all those comments are not breaking. We'll merge this now and fix later today.