chore(linux): Add script to upload to debian

- Create and sign source package
- Upload to mentors.debian.net
- Create (and optionally push) commit with updated changelog file
  based on stable branch
- Create (and optionally push) commit with updated changelog file
  based on master branch

This change also slightly modifies `echo_heading` and outputs a
mark. This will show to the left of the line as well as in the
scroll bar in a terminal in VSCode [[1]] and will help to find the
headings if you have a lot of output in between.

[1]:https://code.visualstudio.com/updates/v1_69#_setmark-sequence-support

(cherry picked from commits ae61410c,
2a55ffb0, 9232c205,
420cc081, 9f7b8583,
and ae0378a5)