dir: Pass environment via bwrap --setenv when running apply_extra
dir: Pass environment via bwrap --setenv when running apply_extra

This means we can systematically pass the environment variables
through bwrap(1), even if it is setuid and thus is filtering out
security-sensitive environment variables. bwrap ends up being
run with an empty environment instead.

As with the previous commit, this regressed while fixing CVE-2021-21261.

Fixes: 6d1773d2 "run: Convert all environment variables into bwrap arguments"
Signed-off-by: Simon McVittie <0e1aea601907c1a85c2dc96e5ea37e23c58d2e9b@collabora.com>

flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak