Output Config Option Values in Canonical Case

[graphemecluster]

This aligns the letter cases of the values in tsconfig.jsons generated by tsc --init and some diagnostics (e.g. TS1501, TS6046) with the autocomplete values provided to tsconfig.json in VSCode and other diagnostics with hard-coded target versions.
This should not affect anything related to value parsing.

Addresses #55600 (comment).

[typescript-bot]

This PR doesn't have any linked issues. Please open an issue that references this PR. From there we can discuss and prioritise.

[jakebailey]

For ecmascript versions I can sort of understand it, but I'm not totally convinced we consider "Node16" more canonical than "node16", "Preserve" etc, https://www.typescriptlang.org/tsconfig/#module

And so on.

[graphemecluster]

I don’t know, I just completely sticked to the autocompletions provided by VSCode (except for a few subtle inconsistencies of lib values, which should be fixed in VSCode). So perhaps changes to the values should be made on the VSCode side synchronically.

[jakebailey]

The autocompletions in VS Code are just the ones from schemastore. Not sure any of us like those either 😄

[graphemecluster]

Oh, I see. Wonder why we didn’t maintain one here or in the VSCode repo.
Anyway, may you give me a list of what should be kept and what should be discarded once there is a consensus on the letter cases? Do you prefer camel case to Pascal case?