feat: Support for ClassInstanceExpr

[shivasurya]

This PR adds support for indexing and querying ClassInstanceExpr

Example:

Source:

Socket so = new Socket("www.google.com", 80)

Query:

FROM ClassInstanceExpr AS cie
WHERE cie.getClassName() == "Socket"
SELECT cie, "Insecure Socket connection found"

[codecov]

Codecov Report

Attention: Patch coverage is 80.21978% with 18 lines in your changes missing coverage. Please review.

Project coverage is 77.74%. Comparing base (e56422a) to head (c03f4b7).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
sourcecode-parser/model/expr.go	23.07%	10 Missing ⚠️
sourcecode-parser/graph/query.go	61.90%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #142      +/-   ##
==========================================
+ Coverage   76.95%   77.74%   +0.79%     
==========================================
  Files          12       12              
  Lines        1410     1492      +82     
==========================================
+ Hits         1085     1160      +75     
- Misses        289      298       +9     
+ Partials       36       34       -2     

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