fix: fix variable definitions inside embedded copybooks

[ap891843]

fix variable definitions inside embedded copybooks.
For below program .

       IDENTIFICATION DIVISION.
       PROGRAM-ID. ABCDEF.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       copy AMAZE.
       copy AMAZE2.
       PROCEDURE DIVISION.

copy AMAZE

       01  CHK-PARMS.
P#1325         07  CHECK    PIC 9(09) COMP SYNC.

copybook AMAZE2

001600 01  META-TABLE.
001700     05  META-FIELD OCCURS 12500 TIMES.
FMC    COPY AMAZE3.
       01  TEST-ULTI pic x.

copybook AMAZE3

         10  META-FIELD-NAME               PIC  X(35).

The produced AST should be like

 
 COPYNODE AMAZE
      | -----> VAR NODE IN SIDE AMAZE COPYBOOK
 COPYNODE AMAZE2
     |-------> VAR NODE IN SIDE AMAZE2 COPYBOOK
     |-------> COPYNODE AMAZE 3
                     |-----> VAR NODE IN SIDE AMAZE3 COPYBOOK
     |-------->  VAR NODE IN SIDE AMAZE2 COPYBOOK

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Check the Use case tests or the PR description

Checklist:

• Each of my commits contains one meaningful change
• I have performed rebase of my branch on top of the development
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have checked my code and corrected any misspellings