Extend APIError to have errors from core

[shuse2]

What was the problem?

APIError did not have enough information to show proper error on the user side.

How did I fix it?

Add errors from APIResponse if exists in the error.

How to test it?

cd packages/lisk-client
npm start
client = lisk.APIClient.createTestnetAPIClient()
client.votes.get({ "random": 1 }).catch((err) => console.log(err.message))
client.votes.get({ "random": 1 }).catch((err) => console.log(err.errno))
client.votes.get({ "random": 1 }).catch((err) => console.log(err.errors))

Review checklist

• Merge After Fix not to expose custom external library definition - Closes #912 #914
• The PR resolves Include all high level error response in APIError #916
• All new code is covered with unit tests
• All new code was formatted with Prettier
• Linting passes
• Tests pass
• Commit messages follow the commit guidelines
• Documentation has been added/updated

[SargeKhan]

Is this test case any useful? Because in the following test, the request is rejected with a defined data property, and the expectation for err.message is the same.

[shuse2]

I think it's useful, because data exists but no message, and no data is treated in the different way in the code