libobs: Resolve bin_path and data_path to absolute paths for modules

[notr1ch]

Description

Many modules create paths based on obs_module_config_path and similar functions, which return a relative path based on the current directory.

This causes a problem on Windows in combination with #11569. The path to the game capture hook DLL is sometimes passed as a relative path when the global hook can't be updated after an OBS update if it's in use. After calling SetDefaultDLLDirectories, the current directory is no longer searched, so the relative path to the hook DLL can't load and we get an inject -4 error.

After this change, inject-helper is launched with both an absolute binary path and absolute argument, so nothing relies on the current directory any more. This commit extends beyond just win-capture though, as any module that was relying on the current directory will now be given absolute paths, which is more reliable in case any random DLL decides to change the CWD.

An unfortunate fixup_path call is needed on Windows, as we have historically only ever used module paths with / as a path separator, and libobs itself also assumes this, so for compatibility we convert Windows \ directory separators back to /.

Motivation and Context

Fix reported inject -4 errors.

How Has This Been Tested?

Forced OBS to inject with local hook DLL and verified full path to inject helper and its arguments were used.

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have read the contributing document.
• My code has been run through clang-format.
• My code follows the project's style guidelines
• My code is not on the master branch.
• My code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.