Add output stream operators for all common types

Add output stream operators for all common types

• include the lightweight <iosfwd> header
• Format output like IDE inlay hints
• add tests for ostream operators

The units library immplements ostream operators for all units, so to me this seems like the logical choice to make our own types printable (contrary to what I proposed in #42 (closed)).

The program was tested solely for our own use cases, which might differ from yours.

Martin Stump martin.stump@mercedes-benz.com on behalf of Mercedes-Benz Tech Innovation GmbH, Provider Information