Remove evaluation by blocks

Introduces AssignExpressionNode and rewrites evaluation of declarations
and references. Closes #4913. Added handling of Static variables.

Author: BZngr

Rubberduck.CodeAnalysis/CodePathAnalysis/Nodes/Implementations/AssignmentExpressionNode.cs

@@ -0,0 +1,9 @@
+using Antlr4.Runtime.Tree;
+
+namespace Rubberduck.Inspections.CodePathAnalysis.Nodes
+{
+    public class AssignmentExpressionNode : NodeBase
+    {
+        public AssignmentExpressionNode(IParseTree tree) : base(tree) { }
+    }
+}

Rubberduck.CodeAnalysis/CodePathAnalysis/Walker.cs

@@ -33,6 +33,10 @@ public INode GenerateTree(IParseTree tree, Declaration declaration)
                 case VBAParser.BlockContext _:
                     node = new BlockNode(tree);
                     break;
+                case VBAParser.LetStmtContext _:
+                case VBAParser.SetStmtContext _:
+                    node = new AssignmentExpressionNode(tree);
+                    break;
             }
 
             if (declaration.Context == tree)