obs-scripting: Add config file functions

[exeldro]

Description

Add config file functions to scripting

Motivation and Context

Allow to read and write config files from scripts

How Has This Been Tested?

On windows 10 64bit with lua code: obs.config_set_uint(obs.obs_frontend_get_profile_config(), "SimpleOutput", "VBitrate", 8000)

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist:

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