Add a "Zapper" function for the liquidity pools.

I propose we add a Zapper function for the liquity pools so liquidity providers can add or remove liquidity in any pool while using 1 type of coin.

Right now if an investor wants to add liquidity to the CAKE-BNB pool, they would need to hold both CAKE and BNB in their wallet. And when they remove liquidity they will get paid out CAKE and BNB tokens.

If we add a zapper function the investor would only need to hold 1 type of coin in there wallet and could use this coin to add liquidity to any pool pancake offers.

We could also add the zapper function for withdrawing tokens and the CAKE rewards from the liquidity pool.

If we add this function then adding liquidity would be simpler for investors as it reduces the amount of operations needed to add / remove liquidity and makes it easier to work out the gains / losses from each investment.

For example, If i held BUSD and i wanted to invest in the CAKE-BNB pool, i would need to convert BUSD to CAKE and BNB (2 transactions), add liquidity (1 transaction) .. wait a few months then withdraw (1 transaction) and convert the CAKE and BNB back to BUSD (2 transactions). for a total of 6 onchain transactions and more time / effot needed to make the investment.

With a Zapper function I could use BUSD to add liquidity to the CAKE-BNB pool and then a few months later i could withdraw my investment in the form of BUSD. This would only take 2 transactions and would make investing more simple.

The zapper fee. We could add a fee for using the Zapper function and use the funds generated to help burn more CAKE. I think a fee of 0.05% would be a fair amount to charge for this service.