Shorthand to query all entities

[0xMochan]

Is your feature request related to a problem? Please describe.

Description

Create a special value ALL that can be used as the first argument in list queries to fetch all entities.

Describe the solution you'd like

Example

swaps = uniswapV2.Query.swaps(
  orderBy=uniswapV2.Swap.timestamp,
  orderDirection='desc',
  first=ALL
)

Originally from: cvauclair