Use snekmate for root address calculation

[stas]

TODO: replace all below with
https://github.com/pcaversaccio/snekmate/blob/main/src/snekmate/utils/create2_address.vy#L49-L76

Consider:

from snekmate.utils import create2_address

@internal
@view
def _root_lp_address(
  _factory: address,
  _token0: address,
  _token1: address,
  _type: int24
) -> address:
...
create2_address._compute_address(salt, init_hash, _factory)

Originally posted by @stas in #90 (comment)

[stas]

You could rewrite the if-else block like this:

common: Bytes[72] = concat(convert(chain.id, bytes32), convert(_token0, bytes20), convert(_token1, bytes20))
salt = keccak256(concat(common, 0x00)) if (_type == 0) else keccak256(concat(common, convert(_type, bytes3)))

Probably the recommended approach consumes slightly more gas, but is definitely more readable imo.

Originally posted by @pcaversaccio in #90 (comment)