fix(lint/noUndeclaredVariables): don't report variable-only/type-only exports

[Conaclos]

Summary

Fix #2637

When the semantic model finds an export it issues two references: a value reference and a type reference.
Only one reference get resolved when the referenced entity is only a variable (value) or only a type.
The remaining reference is forwarded to the parent scope and eventually marked as unresolved.
This is an erroneous behavior for two reasons:

1. An export cannot export a variable/type declared in a parent scope.
2. An export doesn't need to export both a variable and a type.

When we discover an export that exports a type or a variable, we no longer forward and mark as unresolved the dual variable/type.

Test Plan

I added a test.

[github-actions]

Parser conformance results on

js/262

Test result	main count	This PR count	Difference
Total	49701	49701	0
Passed	48721	48721	0
Failed	980	980	0
Panics	0	0	0
Coverage	98.03%	98.03%	0.00%

jsx/babel

Test result	main count	This PR count	Difference
Total	40	40	0
Passed	37	37	0
Failed	3	3	0
Panics	0	0	0
Coverage	92.50%	92.50%	0.00%

symbols/microsoft

Test result	main count	This PR count	Difference
Total	6322	6322	0
Passed	2036	2036	0
Failed	4286	4286	0
Panics	0	0	0
Coverage	32.20%	32.20%	0.00%

ts/babel

Test result	main count	This PR count	Difference
Total	662	662	0
Passed	593	593	0
Failed	69	69	0
Panics	0	0	0
Coverage	89.58%	89.58%	0.00%

ts/microsoft

Test result	main count	This PR count	Difference
Total	17646	17646	0
Passed	13439	13439	0
Failed	4205	4205	0
Panics	2	2	0
Coverage	76.16%	76.16%	0.00%