Debugger: Add options to load extra symbol files conditionally and/or with a base address and more

[chaoticgd]

Description of Changes

• The analysis settings dialog (and the tab in the per-game settings dialog) now lets you specify a base address expression and a load condition expression for each extra symbol file loaded.
• The start and end addresses for function scanning can now also be expressions.
• While working on the above item, I moved the function scanner back to running on the main database rather than the temporary database for the importer. I made the reverse change a while back, but this introduced an issue where user-defined functions would be ignored by the function scanner on repeated analysis runs, so I've reverted it back.
• This exposed a performance issue with running the function scanner on a large invalid address range, hence I've also updated some error handling code in CCC to be more performant.
• The expression parser now accepts symbols with names starting with an underscore.
• CCC now generates a name map for label symbols, allowing them to be used in expressions.
• The expression parser has been updated so that it no longer uses a global variable to report errors.
• The "Remove" button for extra symbol files is now enabled/disabled depending on if a row is actually selected.
• If the specified path for loading an extra symbol file is relative, it is now assumed to be relative to the game settings directory.
• Symbol file paths stored the config file can have either forward slashes or back slashes now, as they are converted into the native operating system format on the fly.

This PR has increased in scope a tad bit since I created it. I will of course incorporate the changes made to CCC here into v2.2 to keep it in sync.

Rationale behind Changes

This is useful for reverse engineering games that use an overlay or dynamic linking system. For example:

Suggested Testing Steps

Someone should make sure all the path handling code works correctly on Windows, including both absolute paths and paths relative to the game settings directory.

[F0bes]

Looks good.
I don't have a test case on me for the overlay condition feature but I am still able to load my external ELF and have the symbols properly imported.