* refactor: move strings declarations to contracts
* feat: added test for FleekSite contract, also did small refactor on SitesNFTs contract test
* refactor: renamed metadadUpdated event due to conflicts
* feat: added test for FleekSite contract
* feat: add fleek site nft interfaces and implementation
* refactor: rename contracts and interfaces
* refactor: replace FleekAccessControl with AccessControl from open zeppelin
* refactor: split structure in public variables
* feat: add Fleek and FleekSite constructors
* refactor: remove getMetadata functions