plugins: Fix missing file descriptors

[WizardCM]

Description

Apply same changes from #1944 to obs-webrtc, obs-vst, and win-capture.

Motivation and Context

Unversioned files are unhelpful, and this makes our DLLs consistent.

Noticed these were missing while comparing the same for obsproject/obs-browser#525.

How Has This Been Tested?

Built on Windows 10, inspected the file details.

Types of changes

• Tweak (non-breaking change to improve existing functionality)

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.