Add basic tests

[bidoubiwa]

Currently this repository has no tests.

The idea is to create a very minimal set of tests on which we can iterate later but that ensures us we did not break the tool.

We need to tests:

• both server endpoints /crawl and /crawl/async
• init of a sender instance
• init of TaskQueue instance
• init of a Crawler instance
• Test the 3 scrapers strategies: default, docsearch, shema
• An end to end tests

To achieve this, we will need to find out how we can mock the servers or run a local playground for testing purposes.