feat: fee token creation

[raul-oliveira]

This PR is part of the fee implementation, it should be merged after the @hathor/wallet-lib since it contains the logic necessary to handle fee tokens.

Acceptance Criteria

• Adds the version field in the create token endpoint. It should forward the version parameter to the @hathor/wallet-lib.
• Adds isomorphic-ws to the devDependencies to fix unit test issues.

Security Checklist

• [] Make sure you do not include new dependencies in the project unless strictly necessary and do not include dev-dependencies as production ones. More dependencies increase the possibility of one of them being hijacked and affecting us.