Add liquidity fee breakdowns

[dib542]

the current endpoints with reserve liquidity:

• /liquidity/pair/{tokenA}/{tokenB}
• /liquidity/pair/{tokenA}/{tokenB}

do no contain Fee information. This is important to the LiquiditySelector component of the web-app which expects a breakdown of the amount of liquidity behind each fee range

this does not have to be on these endpoints, but could be on a different endpoint, eg.

• /liquidity/pair/{tokenA}/{tokenB}/fees
  To give a slice of the liquidity data by just fees instead of by tick indexes (like /liquidity/pair/{tokenA}/{tokenB}) or by tickIndex & fee together which could be a lot of not-so-useful data. these shapes:
  • liquidity by tickIndex: [tickIndex, reserves][] (which is available at /liquidity/pair/{tokenA}/{tokenB})
  • liquidity by fees: [fee, reserves][]
  • liquidity by tickIndex & fees: [tickIndex, [fee, reserves][]],[]