V3 price impact for nested pools

[johngrantuk]

Also refactors nested add/remove to have different pool state for V2/V3. V3 use a new poolState requiring tokens with underlying info:

export type PoolTokenWithUnderlying = MinimalToken & {
    underlyingToken: MinimalToken | null;
};

type NestedPoolBase = {
    id: Hex;
    address: Address;
    type: PoolType;
    level: number; // 0 is the bottom and the highest level is the top
};

export type NestedPoolV2 = NestedPoolBase & {
    tokens: MinimalToken[]; // each token should have at least one
};

export type NestedPoolV3 = NestedPoolBase & {
    tokens: PoolTokenWithUnderlying[]; // each token should have at least one
};

type NestedPoolStateBase = {
    protocolVersion: 1 | 2 | 3;
    mainTokens: {
        address: Address;
        decimals: number;
    }[];
};

export type NestedPoolStateV2 = NestedPoolStateBase & {
    protocolVersion: 1 | 2;
    pools: NestedPoolV2[];
};

export type NestedPoolStateV3 = NestedPoolStateBase & {
    protocolVersion: 3;
    pools: NestedPoolV3[];
};

[brunoguerios]

LGTM 👍