Integrate types for the warn method

[r-52]

This PR consist of two commits (if they are okay, I can them squash them)

1. Mention the id property in the options object of the warn method. The deprecate method mentions the sub-options properties and I tried to align the doc's for the warn method.
2. integrate the Typescript types for the warn method. Right now, the test parameter can be used as a test-condition or as a shortcut for the options object to always display the warning. The options object itself is required for the warning.

What do you think?

[chriskrycho]

Thanks for opening this! One small tweak needed on the TS, and in fact this helps us catch an error in what the types here allowed!

[kategengler]

@emberjs/typescript-core is this relevant?

[gitKrystan]

@emberjs/typescript-core is this relevant?

It should be OK to merge with @chriskrycho's suggestions.

[wagenet]

I rebased and it turns out we'd already integrated most of the changes in other PRs. That said, there are some documentation improvements here that we could merge in.

[kategengler]

Enabled auto-merge!