feat(preset): group Testing Library packages together

[herndlm]

Changes

groups the packages from this kind of monorepo https://github.com/testing-library
See also https://www.npmjs.com/search?q=%40testing-library%2F

Context

I had renovate open one MR for @testing-library/react and one for @testing-library/dom and actually both of those were major upgrades that depend on each other -> need to be done together. So I thought of grouping them by default.

Documentation (please check one with an [x])

• I have updated the documentation, or
• No documentation update is required

How I've tested my work (please select one)

I have verified these changes via:

• Code inspection only, or
• Newly added/modified unit tests, or
• No unit tests but ran on a real repository, or
• Both unit tests + ran on a real repository

[rarkins]

Please add to https://github.com/herndlm/renovate/blob/e17a8a3fd01fc83682f80ea1ca7e4067725ac724/lib/config/presets/internal/monorepo.ts#L549 instead

[herndlm]

sorry about the signed commits showing up as unverified. I recently enabled SSH signing, worked just fine for a privat gitlab, but github is somehow still unhappy with it. even though the ssh public key is trusted in my account, weird. the ssh fingerprint matches and I have no other ssh key on my system it could have used for signing
UPDATE: figured it out, github separates authentication and signing keys :)