fix: detect rules exported using a variable

[bmish]

Updates our rules to detect rules that are defined in variables, which is a style I have seen used by some eslint plugins:

const rule = { meta: {}, create(context) {} }; 
export default rule;

const rule = { meta: {}, create(context) {} }; 
module.exports = rule;

Follow-up to previous work around detecting additional types of rules and variables used inside rules:

• Breaking: Support ESM rules #177
• Fix: Correctly handle rules that are missing meta or have meta / create defined in variables #225

Note that this could be considered either a fix or a breaking change since it will result in additional rules detected by our rules in some plugins.

[aladdin-add]

LGTM, thanks!