Add support for dependencies manifest

[pablochacin]

The binary provisioning can use a dependencies manifest (a json file with dependencies, named package.json by default) to define the dependencies required to execute a test.

This is useful when multiple tests require the same dependencies to avoid having to define them on each test script as pragmas.

However, by default, the dependency resolution logic will look for a manifest in the directory where the test script is located and its parents.

This process is error-prone. In consequence, it has been disabled by default.

It is necessary to define a mechanism to use the manifests safely. For instance, by means of a flag that points to the manifest.