...as long as `brew` is on the path and `brew --prefix e2fsprogs`
tells us where it is.
This is for people who don't have `"$(brew shellenv)"` in their .zshrc.
This patch adds the `find_executable()` function that will hopefully
find executables in a distro-agnostic way and that is (hopefully as
well) easily upgradable.
The function uses some bash functionalities. So, we now require bash
for each script that includes `.shell_include.sh`.
We previously depended on sudo's specific -E flag to keep all the
environment variables when performing a privilege escalation. We now
incorporate the -E flag into the $SUDO variable, allowing for other
privilege escalation binaries (such as doas) to be used (as long as
they preserve the current environment variables).
