[FEAT] Linting rules for describe() depth in tests

[damienwebdev]

I'm submitting a...

[ ] Regression (a behavior that used to work and stopped working in a new release)
[ ] Bug report  
[ ] Performance issue
[x] Feature request
[ ] Documentation issue or request
[ ] Other... Please describe:

Current behavior

Currently, tests don't follow well defined patterns or style guides.

Expected behavior

That tests follow well designed patterns and style guides.

What is the motivation / use case for changing the behavior?

As a start, in addition to the Angular styleguide rules, it would be nice if we could enforce a "describe" depth of 3, which would allow us to do meta-analysis of the complexity of a piece of code.