Renderer: Fix viewport configuration of ArrayCamera.

[Mugen87]

Related issue: -

Description

Whenever a viewport value is configured, the viewport flag must be set to true. Normally the renderer takes automatically care of that but not in the ArrayCamera code path. This broke shadow rendering in the WebGL backend.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	339.51 79.09	339.51 79.09	+0 B +0 B
WebGPU	490.96 136.34	491 136.35	+39 B +4 B
WebGPU Nodes	490.43 136.23	490.46 136.24	+39 B +3 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	465.35 112.14	465.35 112.14	+0 B +0 B
WebGPU	560.26 151.75	560.3 151.75	+39 B +4 B
WebGPU Nodes	516.35 141.53	516.39 141.54	+39 B +4 B