This step converts as many explicit accesses as possible in favor of direct imports from the modules in which things were declared. This restores the code (as much as possible) back to how it looked originally before the explicitify step, e.g. instead of "ts.Node" and "ts.Symbol", we have just "Node" and "Symbol".
This step converts each file into an exported module by hoisting the namespace bodies into the global scope and transferring internal markers down onto declarations as needed.
The namespaces are reconstructed as "barrel"-style modules, which are identical to the old namespace objects in structure. These reconstructed namespaces are then imported in the newly module-ified files, making existing expressions like "ts." valid.
* Change type of deprecated 'decorators' property
* fix 'Invalid Arguments' error for create/update constructor in factory
* Update deprecation comments
* Make 'decorators' optional and 'undefined'
* Rename '_decorators' to 'illegalDecorators'
* Update baselines
* Merge 'decorators' into 'modifiers' on various Nodes
* Drop RESERVED argument in favor of removing parameter
* Ignore grammar error nodes when asserting invariants
* Revert 'illegalX' property renames
* PR Feedback
