refactor: State Streaming Docs + Explicit Config Support (backport #13894)

[mergify]

This is an automatic backport of pull request #13894 done by Mergify.
Cherry-pick of 2c0d445 has failed:

On branch mergify/bp/release/v0.46.x/pr-13894
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Changes to be committed:
	modified:   server/config/config.go
	modified:   server/config/config_test.go
	modified:   server/config/toml.go
	modified:   store/streaming/README.md

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	both modified:   CHANGELOG.md
	both modified:   simapp/app.go
	deleted by us:   simapp/app_legacy.go

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[julienrbrt]

Can we backport stuff with config file changes?

[yihuang]

Just want it remind that state streaming is broken in 0.46 and all the other versions, we should prioritize the fix if we expose the feature through the config @alexanderbez