feat: As a user, I want the contracts data to be indexed via a subgraph

[alainncls]

What does this PR do?

• Initiates a monorepo architecture
• Adds a subgraph to index the creation if the 4 main objects of Verax (Attestation, Module, Portal and Schema).

Related ticket

Fixes #223

Type of change

• Chore
• Bug fix
• New feature
• Documentation update

Check list

• Unit tests for any smart contract change
• Contracts and functions are documented

[codecov-commenter]

Codecov Report

Merging #224 (ddb43e5) into dev (c5c0817) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##              dev     #224   +/-   ##
=======================================
  Coverage   95.26%   95.26%           
=======================================
  Files          11       11           
  Lines         169      169           
  Branches       38       38           
=======================================
  Hits          161      161           
  Misses          6        6           
  Partials        2        2           

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