[Do not merge] Showcase example hooks

[ChefMist]

This PR would showcase some of the hooks we'll use in our workshop

Simple

1. VeCakeSwapDiscountHook: 50% off lpSwapFee if user is veCake holder

Advance

1. VeCakeMembershipHook
   -> swap for token1() will get 5% more token sponsored by hook (hook return delta feature)
   -> for first hour, 0% swap fee for veCake holder

[ChefMist]

close as

1/ outdated

2/ src/pool-cl/VeCakeSwapDiscountHook.sol can be found in #5 instead

3/ src/pool-cl/VeCakeMembershipHook.sol can be in another example hook repository