feat: Implement compiler and virtual machine for Fig language

- Added Compiler class with methods for compiling programs, statements, and expressions.
- Introduced Proto structure to hold compiled bytecode and constants.
- Implemented expression compilation including literals, identifiers, and infix expressions.
- Developed statement compilation for variable declarations and expression statements.
- Created a VM class to execute compiled bytecode with support for arithmetic and comparison operations.
- Added Object and Value classes for handling different data types and memory management.
- Implemented String and Struct objects for enhanced data representation.
- Established a parser for parsing variable declarations and statements.
- Included tests for the VM and object representations.

src/Error/Error.hpp

@@ -41,6 +41,11 @@ namespace Fig
         // parser errors
         ExpectedExpression,
         SyntaxError,
+
+        // compiler errors
+        RedeclarationError,
+        UseUndeclaredIdentifier,
+        NotAnLvalue
     };
 
     const char *ErrorTypeToString(ErrorType type);