Testing the client package

[AlexKushnir1]

Create the tests for client package

The target of this issue is to create unit tests for sertain files like signers, also it seems great to use sandbox from near-workspaces to test actions calling, creating accounts, signing and sending transactions!

This will catch errors while contributing and just prevent issues like this one #1442 when we have a function that doesn`t work

Started working on it