Manage references to element imported from packages.

[suzizecat]

In order to support verification flow (and UVM) there is a need to support both

import my_pkg::* ;
import my_pkg::foo;

Those are managed by, respectively, WildcardImportSymbol and ExplicitImportSymbol.

Explicit import

Explicit import provides a link to the imported symbol. Hence it should be easy to get back the source range, find the undelying IndexSymbol and link.

As of today, the ExplicitImportSymbol is recorded as a new symbol and the local references are bound to it. This will need to be avoided.

Implicit import

Implicit import can lead to the imported (Slang) scope. It can probably be possible to visit this scope and add all symbols definitions to the using file...

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As the package is also present from the top of the index structure, it should be possible to simply add the package name as a lookup location for symbols during the reference matching process.

This should be done on a per-file basis.