Examples: Improve water demo.

[Mugen87]

Related issue: -

Description

The Water2 demos always looked a bit boring so webgpu_water has been updated with a new asset and a basic bloom post processing setup. The old WebGLRenderer demos are removed with this PR.

[mrdoob]

Is there any way to make the water reflection contribute to the emissive pass?
It's weird that the screen blooms but its reflection doesn't.

[Mugen87]

This is tricky. reflector() and viewportSharedTexture() would have to extract the emissive portion which is done differently. reflector() must render its view via MRT and the provide the emissive data for Water2Mesh and viewportSharedTexture() must extract the emissive from the default framebuffer. Only then Water2Mesh can extract the emissive and write it as a result in its shader. That would introduce a noticeable complexity. AFAIC, even Sketchfab does not support this use case. One workaround is to not rely on emissive but apply bloom on the entire luminosity of the scene however that will noticeably brighten the scene in unexpected ways.