Description

This fixes two separate issues that caused obs to potentially crash when creating a toolbar for a source type from a non-loaded module.

• This checks whether a source type does come from a loaded module before creating a special source toolbar for it
• It checks for module existence before trying to fetch a localised string from it in obs_module_get_locale_string

Motivation and Context

Fixes #11457 , and other potential crashes.

How Has This Been Tested?

Ubuntu 24.04 Portable, verified no crash, and toolbar was correctly created/not created.

Types of changes

• Bug fix (non-breaking change which fixes an issue)

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.