Fix analyzer pushing SHADOWED_VARIABLE warning for members shadowed in subclasses

This fixes a bug in the analyzer where it did not push the SHADOWED_VARIABLE_BASE_CLASS
warning for members shadowed by variable in subclass. It does this by comparing the class
which contains the shadowed member with the class containing the variable, and pushing
SHADOWED_VARIABLE only if the classes are the same. Additionally, SHADOWED_VARIABLE_BASE_CLASS
can take an extra symbol which helps to specify the line for non native base class.

modules/gdscript/tests/scripts/analyzer/warnings/shadowning.out

@@ -1,34 +1,46 @@
 GDTEST_OK
 >> WARNING
->> Line: 5
+>> Line: 6
 >> SHADOWED_GLOBAL_IDENTIFIER
 >> The variable "print_debug" has the same name as a built-in function.
 >> WARNING
->> Line: 11
+>> Line: 13
 >> SHADOWED_GLOBAL_IDENTIFIER
 >> The variable "Array" has the same name as a built-in type.
 >> WARNING
->> Line: 12
+>> Line: 14
 >> SHADOWED_GLOBAL_IDENTIFIER
 >> The variable "Node" has the same name as a native class.
 >> WARNING
->> Line: 13
+>> Line: 15
 >> SHADOWED_GLOBAL_IDENTIFIER
 >> The variable "is_same" has the same name as a built-in function.
 >> WARNING
->> Line: 14
+>> Line: 16
 >> SHADOWED_GLOBAL_IDENTIFIER
 >> The variable "sqrt" has the same name as a built-in function.
 >> WARNING
->> Line: 15
->> SHADOWED_VARIABLE
->> The local variable "member" is shadowing an already-declared variable at line 3.
->> WARNING
->> Line: 16
->> SHADOWED_VARIABLE_BASE_CLASS
->> The local variable "reference" is shadowing an already-declared method at the base class "RefCounted".
->> WARNING
 >> Line: 17
+>> SHADOWED_VARIABLE
+>> The local variable "member" is shadowing an already-declared variable at line 4 in the current class.
+>> WARNING
+>> Line: 18
+>> SHADOWED_VARIABLE_BASE_CLASS
+>> The local variable "reference" is shadowing an already-declared method in the base class "RefCounted".
+>> WARNING
+>> Line: 19
 >> SHADOWED_GLOBAL_IDENTIFIER
 >> The variable "ShadowedClass" has the same name as a global class defined in "shadowning.gd".
+>> WARNING
+>> Line: 20
+>> SHADOWED_VARIABLE_BASE_CLASS
+>> The local variable "base_variable_member" is shadowing an already-declared variable at line 4 in the base class "ShadowingBase".
+>> WARNING
+>> Line: 21
+>> SHADOWED_VARIABLE_BASE_CLASS
+>> The local constant "base_function_member" is shadowing an already-declared function at line 6 in the base class "ShadowingBase".
+>> WARNING
+>> Line: 22
+>> SHADOWED_VARIABLE_BASE_CLASS
+>> The local variable "base_const_member" is shadowing an already-declared constant at line 3 in the base class "ShadowingBase".
 warn