Add regression tests for inference bug repros

tests/functional/r/regression_02/regression_dynamic_getitiem.py

@@ -0,0 +1,11 @@
+# pylint: disable=missing-docstring,too-few-public-methods
+
+class DynamicGetitem:
+    def __getitem__(self, key):
+        if key == 'attributes':
+            return []
+        return {'world': 123}
+
+
+ex = DynamicGetitem()
+a = ex['hello']['world']  # [invalid-sequence-index] known false-positive

tests/functional/r/regression_02/regression_dynamic_getitiem.txt

@@ -0,0 +1 @@
+invalid-sequence-index:11:4:11:24::Sequence index is not an int, slice, or instance with __index__:UNDEFINED

tests/functional/r/regression_02/regression_lambda_inference_not_callable.py

@@ -0,0 +1,7 @@
+# pylint: disable=missing-docstring
+
+data = {
+    'abc': None,
+}
+data['abc'] = lambda: print("Callback called")
+data['abc']()  # [not-callable] known false-positive

tests/functional/r/regression_02/regression_lambda_inference_not_callable.txt

@@ -0,0 +1 @@
+not-callable:7:0:7:13::data['abc'] is not callable:UNDEFINED