Merge branch 'main' of https://github.com/codeBigInt/midnight-simplified-tutorial-dapps

migrated code base to preview testnet

Delete demo-tweet-dapp/tweet-contract/midnight-level-db directory

Remove unwanted commited files

Added testnet tested contract, deployment script and contribution guides

Update deployment script

Update project archietecture

Remove rli.js script

Add dployment script

implement witnesses

Add completed tweet contract logic

remove node_modules from repo

add gitignore file to demp

add gitignore file

add initial contract implementation