test: move ts tests in a separate workspace, collect coverage only once

[marcalexiei]

Point 2 of #2142

Typescript tests

Typescript tests have been moved in a separate workspace.
To run them now you have to run npm run test:typescript, as a side effect all ts workspaces no longer have ts- prefix.

CI: Test

Now coverage should be collected only once (when running node 20 matrix value).
On node 18 tests are executed without using coverage.

CI: Typescript

Now CI should be able to test types with both typescript 4 and 5.

See this comment

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

[coveralls]

coverage: 96.191%. remained the same
when pulling 2d94fdf on marcalexiei:feature/tests-improvements
into 3a247e1 on i18next:master.

[marcalexiei]

Looks like testing both typescript supported version is not that simple.
It looks like that typescript doesn't read typesVersion in package.json` locally.

Will think about it and than I'll open a separate PR since it looks more complicated than I expected 😅

[marcalexiei]

Besides typescript issue the optimisation performed has reduced the CI execution time by ~50%:

https://github.com/i18next/i18next/actions/workflows/CI.yml?query=is%3Asuccess

Running test with or without coverage based upon matrix value, avoiding to run runtime and compatibility project twice,
paid off 😀.