Add unit test for WC request handlers

[clemente-xyz]

Description

Wallet Connect's requestHandlers are missing to have unit tests.

The cases are already specified (see libs/wcm/utils/requestHandlers.test.js), but need to be implemented.

Motivation

Wallet Connect feature need to be tested as much as possible to ensure its stability.

Additional Information

Related desktop issue: https://github.com/LiskHQ/lisk-desktop/issues/4715