Moleculer: [lodash] Remove usage of _.defaultsDeep

[abdavid]

See #433 for context.

Describe the solution you'd like
Remove usage of _.defaultsDeep throughout Moleculer, or import the dependency directly without bundling the whole lodash lib.

Describe alternatives you've considered
None so far. I have tested using Object.assign a couple of places where configurations get merged with tests still passing, so that could be feasible.

Additional context
https://github.com/moleculerjs/moleculer/search?q=_.defaultsDeep&unscoped_q=_.defaultsDeep

[icebob]

The problem with Object.assign is that it doesn't copy the object deeply, only the first level. And there are other differences in the logic how they handle arrays, null, undefined.

[abdavid]

I would imagine that would cause some issues. We might need to find a standalon solution to this if we do not conclude with that it is sufficient to include the dependency directly from lodash.

[icebob]

I will write a unit test with _.defaultsDeep with moleculer use-cases, and after that, we will able to create a custom implementation.

[Wallacy]

If want to look this is what i use on my code for merge:

https://gist.github.com/Wallacy/adf546f4de34848e8355d6a511d89647

Should be more simple on pure js; The hard part was be a code with good performance xD;