Consider renaming `EnvironmentMapLight` to `EnvironmentLight`

[tychedelia]

EnvironmentMapLight is wordy and post-deprecation of AmbientLight in #18207 will be more commonly used. We should prefer simpler, shorter names unless the longer name provides sufficiently important descriptive information.

[cart]

I agree this is better!

[JMS55]

I actually like EnvironmentMapLight better. I know it's wordy, but it's specifically about lighting from a texture map (IBL). EnvironmentLight sounds more... general.

[alice-i-cecile]

Blocked until #18207 is merged to avoid conflicts. Then this should be real quick.

[cart]

I actually like EnvironmentMapLight better. I know it's wordy, but it's specifically about lighting from a texture map (IBL). EnvironmentLight sounds more... general.

See this for some thoughts: #18207 (comment)

If we're going to treat it as the "one way to do ambient scene light" I think generalizing is warranted.