Improve type safety and minor corrections

[dj-jayu]

These changes improve code safety and follow C++ Core Guidelines without altering functionality.

Type Safety Improvements:

• Added explicit keyword to single-argument constructors in gs_pattern.h to prevent implicit conversions
• Added std::move semantics to error class constructors (GSError, GSFileError, GSDataError, GSAllocError) for efficient string handling

Modern C++ Keywords:

• Added override keyword to virtual destructors and methods for compile-time checking
• Added default keyword to default constructors and destructors where applicable

Const-Correctness:

• Marked Metrics getter functions as const (get_pattern_size(), type_as_string())
• Marked name getter functions as const (getName(), getShortName(), getShortNameLower())

Initialization:

• Added default initialization (-1) to previously uninitialized member variables in InstrWindow class (iaddr, maddr_prev, maddr)

[Copilot]

Pull Request Overview

This pull request improves type safety and code quality by applying modern C++ best practices and const-correctness improvements without changing functionality.

• Adds explicit keyword to single-argument constructors to prevent implicit conversions
• Implements move semantics for exception class string parameters
• Adds const qualifiers to getter methods that don't modify object state
• Initializes previously uninitialized InstrWindow member variables to sentinel values

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[jyoung3131]

We are reviewing but are not quite sure if we need the override=default line on the destructor. Common C++ guidance seems to indicate this might result in a nop if the code compiles without error (so the line would not be needed at all).

Will review and share some more resources here.