feature request: Add option to no-multi-comp to only count exported components.

[jimbolla]

I'd like to enforce only one exported component per file, regardless of function vs class.

[betaorbust]

This would be extremely useful. In general, we're trying to guard against what a file exports, not the contents of how it builds that export.

[lencioni]

How should such a rule relate to higher-order components?

[ljharb]

I'd think that only the HOC itself would be exported, and so this option would work well with HOCs?

[ThiefMaster]

I'd like to have this as well. I don't want to put "local" components into separate files, so restricting this to exported ones would be very convenient.