Add new demo env that uses faked execution server

[rtorrero]

Initial implementation of a faker to generate data for the checks execution.

It achieves this by providing a implementation for the execution server that instead of triggering executions on agents uses the factories from the tests to generate such results.

[coveralls]

Coverage: 96.309% (+1.07%) from 95.238% when pulling 55b720a on rtorrero:add-wanda-faker into 4c7985b on trento-project:main.

[coveralls]

Coverage: 96.309% (+1.07%) from 95.238% when pulling be28e2f on rtorrero:add-wanda-faker into 4c7985b on trento-project:main.

[fabriziosestito]

Can we randomize the result with https://hexdocs.pm/elixir/1.12/Enum.html#random/1 

You can skip the function parameter and do it directly there

[arbulu89]

@fabriziosestito @rtorrero In our offline conversation, i just was saying, that we can have this execution result coming from the checks results, which now I see is fairly simple. It doesn't need to be random.
You just need to loop through the check results, check the result of them, and simply weight them (or some basic operation to find the worst check result).
Anyway, I'm fine on improving this on future iterations

[arbulu89]

I find the current implementation too dump honestly.
We need to think on having certain logic like:
If the expectations are true -> the result of the check is true, etc
We cannot have failed expectations and passing results.
Now that we will implement the new view of the results using all these data, it would look totally illogical.

I think that we need to invest much more on this.
If you want to do in a subsequent PR is still good.

[arbulu89]

Thanks @rtorrero
I still think that there are unfinished things, but I'm fine merging this first to at least enable the demo environment, and we can work on it later at some point

[arbulu89]

LGTM.
Some few typo,copy/paste and linting errors.
You need to add the demo folder to the .formatter.exs and .credo.exs file, to be included in the checks