More clang-format pipeline changes

[haenkel]

• use clang-format-12 in pipeline (github actualy uses 11 as the 20.04 default)
• 11 and 14 create output like this:

{{// FLT
  morph_group_2-> ...
morph_group_2-> ...

• reformat and turn it off wherever 14 would break things
• message what we are using
• this needs a better solution going forward