Improve easycrypt config to better reflect project file configuration

[fdupress]

When in a folder controlled by an easycrypt.project file, it would be nice to ensure that the config printed by easycrypt config reflects all options set by the project.

At the moment, load paths are displayed as defined, but

1. The project file being read is not listed;
2. There is no difference between known provers that will not be used and the known provers that have been selected by the config; and
3. Options set by the project file are not displayed. (It could just be added as a "default options" line, which could also reflect global config options?)

[strub]

The project file is found relatively from the compiled file name.

[fdupress]

I think we could assume (for this purpose) that easycrypt config is run in the folder where the compiled file would be.

The use case here is to properly display actual options in CI logs.