[TASK]: SIP-184 Dynamic Fee

[andytcf]

Summary

SIP - https://sips.synthetix.io/sips/sip-184/ PR - https://github.com/Synthetixio/synthetix/pull/1563

• [x] Feasibility
• [x] Implementation
• [x] Gas instrumentation
• [x] Testing
• [x] Audit

[andytcf]

https://github.com/Synthetixio/synthetix/pull/1563

[andytcf]

• [x] Params.json (L1)
• [x] first implementation
• [x] Performance - have lastDynamicFee and lastRoundSeen for caching
• [x] Merge develop once https://github.com/Synthetixio/synthetix/pull/1127 merged
• [ ] Unit test
• [ ] Add more test scenarios.
• [ ] integration test
• [ ] Audit
• [ ] Testnet deploy