obs-vst: Remove submodule in favour of direct merge

[WizardCM]

Description

This deletes the submodule of plugins/obs-vst in favour of being included in the main repo.

IMPORTANT: Developers will have to delete the obs-vst folder manually before pulling these commits, otherwise Git will error.

This also removes its custom .clang-format file in favour of using the main repo's, alongside the README and License file.

Motivation and Context

obs-vst is first party, and including it as a submodule introduces a lot of unnecessary headaches.

How Has This Been Tested?

• Build OBS

Types of changes

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

Checklist:

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

[Conan-Kudo]

Is this okay with the Steinburg header dependency?

[dodgepong]

obs-vst doesn't use any Steinberg headers. It uses headers from LMMS.

[gxalpha]

Just as a heads-up when rebasing this against master: The cmake rewrite added a check for whether the submodule files exist which now can get inlined to just add_subdirectory(obs-vst) with this PR.

[WizardCM]

Per @gxalpha's comment I've made the relevant additional changes. Would love it if a second person could test this.

I do fear users may potentially have to

• delete .git/modules/plugins/obs-vst
• run git config --remove-section submodule.plugins/obs-vst

[Chiitoo]

Without removing the deletion of plugins/obs-vst from the patch I'm getting File plugins/obs-vst is not a regular file -- refusing to patch (with and without cloning the obs-vst repository).

Other than that, seems to work for me so far.

[gxalpha]

Sorry for being unclear, what I meant was just "replace each check_obs_vst() call with add_subdirectory(obs-vst)". To me at least it looks like obs-vst is disabled on purpose on FreeBSD/OpenBSD, so the differentiation between the operating systems is probably still needed.

[RytoEX]

Per discussion off-thread, this will need to be two commits: one which deletes the submodule, and a second one which merges the submodule into the tree.