feat: liquidity mechanisms overhaul

[cdummett]

closes #2253
closes #2268

Warning

This PR will make the new liquidity reward metric #2266 redundant as the existing liquidity fees metric will no longer be abused from wash trading.

Instead #2309 should be merged, as this introduces an alternative method for the new liquidity reward metric where rewards are distributed pro-rata by the volume of notional each LP provides.

Summary

PR deprecates previous liquidity specs and replaces them with simplified liquidity mechanisms which:

• require no bond
• require no sign-up transaction
• yields more predictable liquidity fees

In short the mechanics work as follows...

• parties accrue ELS points over time proportional to their maker fees earned.
• parties are designated as LPs on an epoch by epoch basis if they receive above a specified proportion of the markets maker fees.
• parties receive a proportion of the liquidity fees accumulated in an epoch relative to their accrued ELS points and volume of notional (but only when designated as an LP).

Open questions:

1. Points accrued and LP designation driven by maker fees received - how open is this to abuse through wash trading?
   • Resolved: with introduction of "volume of notional" weighting
2. Does this incentivise deep books? - advantageous for minimal slippage and quick disposal of network position.
   • Resolved: with introduction of "volume of notional" weighting
3. Does this incentivise being on the book throughout the epoch enough?
   • Resolved: with introduction of "volume of notional" weighting

[witgaw]

LGTM