Replace release.mk by release scripts

Since commit 2687d202809dfaafe8f40f613aec131ad9501433, the Makefile
named release.mk stopped handling dependencies between recipes, because
they have to be executed separately (from different Github Actions
jobs).

Using a Makefile no longer provides any real benefit. Replace it by
several individual release scripts for simplicity and readability.

Refs #5306 <https://github.com/Genymobile/scrcpy/pull/5306>
PR #5515 <https://github.com/Genymobile/scrcpy/pull/5515>