Add regression tests for macro expansion #744

Part of replacing the macro expansion (see #742).

Before the macro expansion is refactored and replaced, its current behaviour needs better test coverage so that changes in later PRs can be checked against it. This PR only adds and adjusts tests. There are no changes in simplecpp.cpp.

Tests added

• Examples 3, 4, 5 and 7 from C11 6.10.3.5.
• The C23 __VA_OPT__ examples.
• Invalid ## pastes.
• Token::macro, the locations of expanded tokens, and the macro usage, which cppcheck uses. A new helper expandedTokens() writes each output token with its macro name and location, and the tokenMacro tests use it.