Update plugin paths to new first-party paths

[RytoEX]

Description

Due to obsproject/obs-studio#13594 , the paths for first-party OBS Studio plugins has changed. This causes two failures:

1. bouf fails to copy the core directory when preparing the files
2. bouf/NSIS fails to generate the installer

Motivation and Context

Want bouf and NSIS to work so we can generate the installer and ship updates.

There are other opportunities for clarification and cleanups here, but I want to keep this minimal.

This may cause merge conflicts with other PRs, which I may have to resolve later.

How Has This Been Tested?

Tested locally on Windows 11 with a local build of bouf with these changes against CI artifacts from obs-studio for OBS Studio 33.0.0-beta3.
https://github.com/obsproject/obs-studio/actions/runs/36089668738/attempts/1

I have not tested patch generation.

Types of changes

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

• 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.