fix: handle properties behind spread syntax in require-meta-* rules

[bmish]

We're now able to take into account meta properties inside spreads in the require-meta-* rules.

1. Introduces new util function evaluateObjectProperties which gathers all properties from an object including those behind spreads.
2. Uses this new util function when checking for properties inside the meta object in the require-meta-* rules.

Fixes #250.

Example: this is now valid for the require-meta-type rule:

const extra = { type: 'problem' };
module.exports = {
    meta: { ...extra },
    create(context) {}
};

TODO:

• Unit tests for evaluateObjectProperties util
• Check for additional places we should evaluate spreads
• Tests for autofixing behavior when properties are behind a spread

[bmish]

Ready for review.

[aladdin-add]

LGTM, thanks! 💯

[piranna]

great :-)