Credits system

[eskimor]

RFC-5 specifies that instantaneous core time should be bought via credits.

• Keep track of credits in on-demand
• Implement credit_account
• Allow extrinsic using credits instead of raw balances to pay for an instantaneous core

[eskimor]

Note, I just realized that this is more urgent than I thought: While credits are strictly speaking useless right now, they are implemented on the coretime chain: People can credit an account. Without this being implemented, those funds would be stuck and entirely useless.

Therefore:

1. We either remove that feature for the time being on the coretime chain or
2. We just implement this feature already.

[Overkillus]

Current consensus is that the relay chain will use native DOT tokens for on-demand coretime purchases. Credits will be revisited when balances will move off the relay chain in the future. Until then this issue can be de-prioritised or closed.

[bkchr]

Current consensus is that the relay chain will use native DOT tokens for on-demand coretime purchases.

I don't see this as a consensus. I personally still don't see any reason why we should do this. Especially as we want that these credits are not used for anything different, which would not be the case when using the native token.

[seadanda]

Since one of the main aims of the asset hub migration is to move away from pallets requiring balances on the Relay Chain, we should re-prioritise this issue.