Refactor event and tasks

[NicolasMahe]

No description provided.

[NicolasMahe]

I updated this PR:

• I create a new file contract/parseEvents.ts that only normalize event from ethereum (convert timestamp to date, unit 'wei' to 'ether', hex to ascii, hash to base58, etc..)
• I moved the logic about event from index.ts to events/index.ts. I keep the same logic: this file map smart contract event to individual event handler. Each event handler then emit to mesg (if they want to) and parse the event using the functions in first point.
• I also moved the logic about task from index.ts to tasks/index.ts. No logic changed.

@mesg-foundation/core please review

[antho1404]

I like the simplification of the index :) it was really messy

[ilgooz]

manual tests are ok