Add renderer for drawing event points

[kyasbal]

This PR adds renderers specific to draw rectangles for revisions.

This PR depends #463 and includes the changes introduced in #463. This would be merged after rebasing this on #463 once the parent review is done.

[gemini-code-assist]

Summary of Changes

Hello @kyasbal, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly upgrades the timeline's rendering capabilities by introducing a new WebGL-based event renderer. The changes focus on improving performance and enabling advanced visual effects and interactivity for timeline events. It establishes a robust foundation for future graphical enhancements by centralizing WebGL utilities, implementing an efficient hit-testing mechanism, and structuring event rendering with instanced drawing and dedicated GLSL shaders.

Highlights

• WebGL Utility Class: Introduced WebGLUtil to centralize common WebGL operations such as compiling/linking shaders, loading textures, and parsing BMFont configurations.
• WebGL Hit Testing: Implemented a shared resource (TimelineHitTestSharedResource) for efficient WebGL-based hit testing, utilizing a framebuffer object (FBO) and a texture to map screen coordinates to timeline elements (revisions, events).
• Timeline Event Renderer: Developed a dedicated WebGL renderer (TimelineEventsRenderer) for timeline events, leveraging instanced drawing with Vertex Array Objects (VAOs) and Vertex Buffer Objects (VBOs) for high-performance rendering and dynamic updates based on interaction states.
• GLSL Shaders for Events: Added a suite of GLSL shaders (event-v2.vertex.glsl, event-v2.color-fragment.glsl, event-v2.hittest-fragment.glsl, event-v2.shared.glsl, v2.shared.glsl) to define the visual appearance, interaction feedback (hover/selection), and hit-testing logic for timeline events.
• Shared Timeline Resources: Enhanced shared rendering resources (TimelineRendererSharedResource) to include MSDF font textures for numbers and icons, along with a uniform buffer object (UBO) for global view state, ensuring consistent and efficient data access across different renderers.

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[gemini-code-assist]

Code Review

This pull request introduces a new WebGL-based event renderer for the timeline (v2). The changes include new TypeScript files for WebGL utilities, shared resources for rendering and hit-testing, and the event renderer itself, along with the corresponding GLSL shader files. The implementation is comprehensive, covering color rendering, hit testing, and dynamic style updates. My review focuses on improving performance through parallelization of asynchronous operations, increasing robustness by adding necessary checks and safer data handling, enhancing maintainability by reducing code duplication, and fixing minor issues in the shader code. Overall, this is a solid addition, and the suggested changes will help make the new renderer more performant and resilient.