types: support nested keys in InterpolationMap

[marcalexiei]

Fixes #2014

Now InterpolatorMap parse the keys retrieved via ParseInterpolationValues creating a mapped type instead of a a Record<string, unknown>.

Here is a typescript playground where all types involved are available:

• Open Playground
• Scroll down and edit string type on line 50 (Ret type)

From my basic test this shouldn't affect performance very much,
but I haven't conducted deep performance test so far.

Unfortunately this I haven't a real app scenario to test this since
I am not using JSONs for translation so all my values are string.

If someone with the issue could test this it would be great.

Checklist

• only relevant code is changed (make a diff before you submit the PR)
• run tests npm run test
• tests are included
• commit message and code follows the Developer's Certification of Origin

---

Off topic

@adrai sorry if I write here but I don't know a better place 😅
Thanks for the invite! I have a few ideas to share about some changes to the library and repo,
if is ok for you I'll open an issue with more details in the upcoming days.

[coveralls]

coverage: 96.188%. remained the same
when pulling 801f461 on marcalexiei:feature/interpolator-map-nested
into 2f3384b on i18next:master.

[adrai]

thank you @marcalexiei.... it's included in v23.9.0