feature: 🍺 Class with inheritance support

[shivasurya]

Description:

Adding support for class with inheritance. Upon implementation,

class SSRFBase {
  string getName() {
    result = "Generic SSRF Sink"
  }
}

// Derived class
class SSRFSink extends SSRFBase {
  string getClass() {
    result = "Request"
  }
}

predicate isSink(Node obj) {
  obj instanceof SSRFSink
}

// Query to use the predicate
from SSRFSink a
where isSink(a)
select a, a.getClass()

Checklist:

• Tests passing (gradle testGo)?
• Lint passing (golangci-lint run this requires golangci-lint)?