feat(sessions): implementing session create, list and get handlers

[geekbrother]

Description

This PR implements the following handlers according to the sessions API spec:

• Session/permission creating at POST /v1/sessions/:address,
  • Generating the ECDSA keypair, storing the verification key (for further owner verification), and returning the signing key.
  • Generating the unique PCI (permission identifier) by using the UUIDv4 format.
  • Storing the permission object in the IRN.
• List of session/permissions PCI (permission identifiers) for the certain address at GET /v1/sessions/:address,
• Get session/permission by the address and PCI (permission identifier) at GET /v1/sessions/:address/:pci.

How Has This Been Tested?

• Integration tests for creation, list, and get were implemented.

Due Diligence

• [ ] Breaking change
• [ ] Requires a documentation update
• [ ] Requires a e2e/integration test update

[chris13524]

Generating the unique PCI (permission identifier)

Why is it called PCI? There is no c in permission identifier

[geekbrother]

Generating the unique PCI (permission identifier)

Why is it called PCI? There is no c in permission identifier

I'll update comments with C description as well )). PCI is a Permission Controller Identifier.