Avoid per-frame delegate allocation in render-data lookups

[FMsongX2]

Summary

Replaces capturing-lambda Array.FindIndex calls on the per-frame render path with allocation-free for loops, removing a Predicate<T> delegate allocation on every call. No behavior change.

Problem

CubismRenderController.OnDynamicDrawableData — invoked from CubismModel.Update() every frame — locates the renderer for each drawable with:

var rendererIndex = Array.FindIndex(renderers, cubismRenderer => cubismRenderer.Drawable.UnmanagedIndex == dataIndex);

It runs in three loops over all drawables, once per drawable before any dirty check — 3 × drawableCount times per frame. The lambda captures the loop variable dataIndex, so the compiler cannot cache it as a static delegate (only non-capturing lambdas are cached); a Predicate<T> is allocated on every call. CubismRenderingInterceptController.TryDraw has the same pattern, capturing currentCamera.

Changes

• OnDynamicDrawableData: the three loops share one allocation-free IndexOfDrawable helper (a plain for loop) instead of the capturing Array.FindIndex.
• TryDraw: the capturing Array.FindIndex over _cameraDrawStatus is inlined as a for loop.

Why this is safe

Functionally identical to Array.FindIndex: it returns the first index whose Drawable.UnmanagedIndex matches dataIndex (or the first entry whose Camera matches, for TryDraw), or -1 when none matches; the existing < 0 handling is unchanged. The lookup is still resolved by Drawable.UnmanagedIndex exactly as before. No public API or behavior change.