Run integration tests with coverage against `spine-web` source code.

[YegorUdovchenko]

Currently, integration tests defined in web-tests module use the unpublished artifact of spine-web library for tests. It was made to test the library in a way it is used by end-users. This approach caused the decrease of test coverage in client-js module because integration tests are not running over its source code any more.

One of possible solutions to recover test coverage is to make integration tests run over the spine-web artifact in a test mode (as it is now) and to run the same tests over the spine-web source code in a coverage mode.

The issue is to expand web-tests module and switch between spine-web artifact and its source code to run tests. The possible solution is to install spine-web source code as web-tests dependency by path as follows:

"spine-web": "file:../../client-js/main/"