Split examples and templates aka showcases

Adapt the repository tree such that we have the following directory tree:

• examples
• tex
• templates

Remove empty directory doc add a new directory templates

Policy for files in directory examples:

• Holds a minimal example and the documentation of a certain BFH-CI LaTeX class.
• It is one file prefixed with "DEMO-"
• Shows the user how a certain class/package works
• As less 3rd party packages as possible
• No sub-directories allowed (flat structure used also for testing)

Policy for files in directory templates:

• Holds templates for different use-cases using bfh-ci.
• Each use-case is in its dedicated sub-directory and may contain a directory structure.
• The intent of the use-case templates is to help a user to get started quick using bfh-ci for i.e. creating a project report, a paper, a fact-sheet, or a BSc / MSc thesis.

Adaptation of CI pipeline will be required as well as a modification of the table generator implementation -- see issue https://gitlab.ti.bfh.ch/bfh-latex/version-table-generator/-/issues/6