feat(rule): add prefer-inline-decorator rule

[rafaelss95]

This ensures that decorators are on the same line as the property it decorates.

Failure example:

@Input()
x: string;

Success example:

@Input() x: string;

Closes #549.

Note that I've tried to implement a fix for this. Let me know if I did something wrong.

[rafaelss95]

@mgechev:

About the name: not sure if it's the best, you can suggest another one.

---

I implemented it for all "property" decorators, does it makes sense to add it for "method" decorators, as @HostListener, for example?

It would fail in this case:

@HostListener('keydown')
newColor() {
  // something nice here
}

... but not for this:

@HostListener('keydown') newColor() {
  // something nice here
}

If so, what would be the best way to setup?

"prefer-decorator-inline": true // no difference for methods or properties decorators

vs

"prefer-decorator-inline": [true, "properties", "methods"] // you can disable one of them based on your needs

---

I've tried to verify the case I described in #549 (comment), however it seems that this case does not trigger either the visitPropertyDecorator method or the visitNgInput method, so I'm stucked.

[wKoza]

sure, implement this for method make sense. @HostListener is good candidate.
Concerning the configuration of the rule, the global approach seems the best way since we want to identify easily the role of an input / method.

[mgechev]

Good job! Left two minor comments.

[mgechev]

I'd call it prefer-inline-decorator.

[rafaelss95]

Done.

[mgechev]

It makes sense to allow rule configuration (i.e.blacklist decorators for example).

[rafaelss95]

Done.