- adjust GithubIssue models to include a label array -
  moves the label element from GithubIssue to GithubIssueReduced (indirectly in GithubIssue still through extension) (`github-issue.model.ts`)
- get them from the graphQL API (`gihub-issue-map.util.ts`)
- add labels with a private helper function as tags (with import of name and color)
  using TagService utilities (`gihub-common-interfaces.service.ts`)

part of the implementation regarding johannesjo#2866

- add config member for a flag to import labels as tags or not (`github.model.ts`)
- set default for that config member to false and add to UI form (`github.const.ts`)
- add const elements for that form to be filled in with translation elements/values (`t.const.ts`)
- first formulations of form elements in english and german (`en.json`, `de.json`)

part of the implementation regarding johannesjo#2866