* Allow redeclaring CommonJS alias with initial undefined
This allows us to read our own output, plus the times when people
manually write exactly the same pattern.
Fixes#40555
* Use control flow to type commonjs exports
1. Could probably use a *lot* more tests.
2. getTypeOfAlias redoes some work from resolveAlias because it needs to
not resolve the alias completely, just to its export.
* fix lint, improve jsdoc
* Add tests, improve+fix control flow
1. Update the module.exports test to match the exports ones.
2. Add a test of evolving commonjs type.
3. Add a test of assignment as last statement.
(1) exposed a bug that required a better synthetic reference. (3)
exposed a bug that was most easily fixed by giving source files a
`endFlowNode` like functions and setting it in the binder.
* fix lint
* Fix error on duplicate commonjs exports
Previously, the code missed setting the parent pointer for the lhs
access expression.
Also add declaration emit of element access expressions, missed in my
previous PR.
* Switch to excludes=None, add test case
CommonJS exports have None excludes, but still have an error issued by
the checker. This is the previous behaviour even though it would be nice
to add some exclusions.
