While at it, also remove unnecessary "#!/usr/bin/env python3" in files
that only get imported, and adjust other empty/comment lines in the
beginnings of the files for consistency.
This makes files easier to read, and makes the pmbootstrap codebase more
consistent with the build.postmarketos.org codebase.
* moved export code to pmb/export and split it up
* added deprecation notice to "pmbootstrap flasher export"
* made "pmbootstrap export" work
* adjusted the "pmbootstrap flasher export" hints in the code
Oliver Smith
Oliver Smith