Because GitHub's Ubuntu image offers multiple version fo clang-format, and
sometimes it seems to prefer a version lower than 12 (which is the minimum
required by our config file), I added an override via the new environment
variable `KALEIDOSCOPE_CODE_FORMATTER`.
Signed-off-by: Michael Richters <gedankenexperimenter@gmail.com>
I added a `.clang-format` file to try to get as close as possible to our current
code formatting. I also updated the makefile targets and the github workflows.
Signed-off-by: Michael Richters <gedankenexperimenter@gmail.com>