Separate Matchers between browser, element and mock matchers

[christian-bromann]

Currently we have one single interface for all matchers. This causes the following to not fail:

expect($('foobar')).toHaveUrl('...')

We should create browser, element and mock matchers to be more explicit about the available matchers based on provided object.

[christian-bromann]

Made an attempt on this in the cb/separate-matcher branch. Unfortunately if we want to conditionally extend matchers based on the passed in generic it would mean we have to transform the Matchers interface to a type which means that:

• users can not extend matchers based on current docs (changing it would be a breaking change)
• we couldn't extend other matchers anymore e.g. extend Jest matchers with WebdriverIO ones

Regarding latter, I am not sure how many folks actually have this use case. This library started as a basic extension to Jest matchers and would develop with this change to an assertion library useful WebdriverIO only.