obs-filters: Add white balance filter

[mar10iana]

Description

This PR introduces a new White Balance Filter for OBS Studio by adding white_balance_filter.c and white_balance_filter.effect.

This filter allows users to fine-tune red, green, and blue balance using three sliders. It applies a color transformation matrix to adjust white balance dynamically for more accurate color correction.

The filter consists of:

• C implementation (white_balance_filter.c)

  • Registers a new filter with three adjustable sliders.
  • Applies a color matrix transformation based on user input.

• Shader effect (white_balance_filter.effect)

  • Applies the color matrix correction in the pixel shader.

Motivation and Context

Currently, OBS offers a variety of color correction filters but lacks a dedicated white balance feature, which is essential for many users. This feature aims to address this issue by introducing a White Balance option in the Filter menu.

Ideas website link: White Balance Feature Request

How Has This Been Tested?

• Platform: macOS
• Steps to Test:
  1. Add a new Filter to a source.
  2. Select White Balance Filter.
  3. Adjust the Red, Green, and Blue sliders.
  4. Observe real-time color correction.

Types of changes

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

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.

[mar10iana]

Hey @Warchamp7, can you review this version of the white balance filter please?
I am sorry for making a new PR.