Refactor: Pass std::string_view by value instead of by const reference

[leejkee]

Refactor: Pass std::string_view by value instead of by const reference

Closes #1259.

As discussed in Issue #1259 , this PR refactors the codebase to pass std::string_view by value (e.g., std::string_view) instead of by const std::string_view&.

Changes Made

• Updated HeaderCallback's std::function and operator() to use std::string_view.
• Updated DebugCallback's std::function and operator() to use std::string_view.
• Updated WriteCallback's std::function and operator() to use std::string_view.
• Updated relevant unit tests to use std::string_view in their lambda signatures.

[COM8]

Approved. Thanks @leejkee for your work!