feat(perp): settle markets

[Unique-Divine]

Context

Adds initial settlement price calculation (in draft) for continuation by @jgimeno. Please see this GH issue for more info.

Purpose

• docs(perp): Write math reference for the settlement and market versioning #1551
• epic: feat(perp): SettlePosition tx #1474

Changes

• feat(perp): impl AMM.SettlementPrice func #wip
• refactor(perp): rename amm.MarkPrice -> amm.InstMarkPrice to reflect that it's instantaneous
• test: add table tests for the settlement price calculations
• docs: document the feature in the GH issue and in markdown

[codecov]

Codecov Report

Merging #1573 (f271a00) into master (ef307eb) will decrease coverage by 0.47%.
The diff coverage is 72.58%.

❗ Current head f271a00 differs from pull request most recent head 812fc4b. Consider uploading reports for the commit 812fc4b to get more accurate results

@@            Coverage Diff             @@
##           master    #1573      +/-   ##
==========================================
- Coverage   74.49%   74.02%   -0.47%     
==========================================
  Files         175      177       +2     
  Lines       14567    14335     -232     
==========================================
- Hits        10852    10612     -240     
- Misses       3097     3120      +23     
+ Partials      618      603      -15     

Files	Coverage Δ
x/perp/v2/keeper/amm.go	92.10% <100.00%> (+0.92%)	⬆️
x/perp/v2/keeper/calc.go	94.54% <100.00%> (ø)
x/perp/v2/keeper/grpc_query.go	70.07% <100.00%> (ø)
x/perp/v2/keeper/keeper.go	96.55% <100.00%> (+4.12%)	⬆️
x/perp/v2/keeper/liquidate.go	79.05% <100.00%> (ø)
x/perp/v2/keeper/margin.go	74.80% <100.00%> (ø)
x/perp/v2/keeper/swap.go	100.00% <ø> (ø)
x/perp/v2/keeper/twap.go	86.95% <100.00%> (+0.14%)	⬆️
x/perp/v2/module/genesis.go	98.09% <100.00%> (+0.05%)	⬆️
x/perp/v2/types/genesis.go	85.36% <100.00%> (+5.36%)	⬆️
... and 7 more

... and 23 files with indirect coverage changes