Add dead link checker in score and internal repos

[TimoSteuerwaldETAS]

What

A dead link checker would be good for all kind of documentation in our repository.

Links could outdate for various reasons, incl. renamed or deleted requirements, external ressources not under our control, etc.

Therefore nvestigate if bazel target docs_link_check would be a possible solution, see here.

See also discussion in internal repo here.

In case if the access is prohibited, this is the google result.
Lychee looks promising!

Acceptance Criteria (DoD)

External link checker is established in a pipeline job.

How

No response

[TimoSteuerwaldETAS]

For now docs_link_check has been added to the internal docs pipeline build:
https://github.com/etas-eng/vsps_lifecycle_docs/pull/27/changes/d8dfed5e2495e5c45643b6e86b4b0f839b9c3bce#diff-d7a404dd48e4f5ce8cde01bfffc9b4ede2bce99c11e69505d443626af6567425R13

TBC: Clarify how often it should be executed in lifecycle repo.
In docs-as-code repo this is executed weekly: https://github.com/eclipse-score/docs-as-code/blob/main/.github/workflows/link_check.yml