Add smoke tests

[ErikSchierboom]

• Exclude more files from Docker build context
• Add scripts to run tests
• Add smoke tests to CI
• Move input.ex files to lib directory for test data

I've tried to keep the existing structure as much the same as possible.

[ErikSchierboom]

@angelikatyborska Would you mind taking a look?

[angelikatyborska]

I'm pretty busy in the next 7 days, maybe @jiegillet can review?

[ErikSchierboom]

Thanks all!