Update node to 18

[kernicPanel]

Purpose

On our last js update, jwt-decode dropped support for node 16. As node 16 reached EOL, and as we're still stuck to v18 in AWS lambda image, we want to upgrade to 18.

Proposal

• [x] Update node to 18
• [x] Update jwt-decode to 4
• [x] Remove mostly useless tests incompatible with node 18 (jest screenshots)
• [x] Specify node version through volta
• [x] Cleanup yarn.lock