[kg] [kotlin] Index cross-file references

Problem to Solve

We have built a solution that supports indexing the contents of a single file, but we now need cross-file resolution to have the full context of the codebase.

Proposed Solution

• Parse the expressions using the Code Parser.
• Build a global symbol table that is scoped based.
• Get expressions from the Code Parser and resolve the definition referenced for calls using the global symbol table.
• Save the Calls relationship between definition nodes.