Transform checker check root unresolved references.
The transform checker is now checking pretty much everything it can.
Only fields of `ScopeTree` and `SymbolTable` that it's *not* checking are those which contain `AstNodeId`s, because transformer does not create node IDs at present:
* `ScopeTree::node_ids`
* `SymbolTable::declarations`
* `Reference::node_id`
Checking also only proceeds in "from AST" direction.
i.e. for each `SymbolId` which appears in the AST, we check everything about that symbol. But we *don't* go through all the "rows" in `SymbolTable` and check if there are any extra symbols in the table which aren't in the AST.
Presumably transformer will leave a lot of old symbols lying around in `SymbolTable` (ditto scopes and references). We'd need to add `ScopeFlags::Deleted`, `SymbolFlags::Deleted` and `ReferenceFlags::Deleted` for the transformer to be able to "delete" existing symbols.
closes https://github.com/oxc-project/oxc/issues/4790
@overlookmotel enjoy ... take a look at the snapshots and probably nothing else.
The snapshots are minimal right now, but it's already showing symbols from import specifiers are not being removed. We can iterate on the snapshot representation to aid debugging later.
I'll extend this to `transformer_conformance` and `oxc-monitor` in an up coming PR.
