Adjusted the generation of cpp templates to be valid cpp

[mamueluth]

• Changed the name for placeholders like $ClassName$ to valid cpp syntax.
• Adjusted workflow to include templates/ dir for cpplint
• Added genuine licenses which is replaced in process. This is done by deleting the old one in the respective file. As a result, the Apache License, Version 2.0 needs to be present in exact form otherwise this could lead to deletion of unintended lines.
• Currently, ament_copyright won't recognize the Apache License, Version 2.0 in the given form. Couldn't find a difference, so I am not exactly sure why this is the case. The c++ files are therefore still excluded from the check. However, ament_cpplint checks this anyway (but only in a very rudimentary way). Seems to work now with only one copyright line at beginning
• python files don't include license as of now, but are generated with different scripts. Could be changed in future

[mamueluth]

NOT tested so far. Besides, ament_copyright won't recognize license...

[mamueluth]

Tested, should work. However, running the tests for controller and hardware interface before merging is highly recommended.

[mamueluth]

Please verify that generation of controllers and especially hardware is working as intended.