[docs-infra] Move ApiPage to TS

[alexfauquette]

Extracted from #43128

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I tried to move useTranslate from (key, options) => any to (key, options) => string. But some part of the codebase rely on it returning null is the key translation is not defined (the API pages titles) and (key, options) => string | null leads to a lot of place where t('...') needs to be marked as non-null t('...')!. SO I dropped this idea

[mui-bot]

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[Janpot]

But some part of the codebase rely on it returning null is the key translation is not defined (the API pages titles) and (key, options) => string | null leads to a lot of place where t('...') needs to be marked as non-null t('...')!.

Perhaps it could make sense to have two complementary functions? One that throws and one that returns null when a translation doesn't exist. The throwing one can then have return type string. This is a bit like the react testing library approach of using getBy vs. queryBy. In terms of implementation, one can be built on top of the other, so no duplication required. A potential API:

const t = useTranslate()

const maybeString: string | null = t('abc')
const certainlyString: string = t.require('xyz')

[Janpot]

Looks all good to me, everything strongly typed. Left one suggestion about solving the types of the translation function