cargo pgrx test --runas envar passing

[eeeebbbbrrrr]

This teaches the test framework.rs to pass through to sudo all the various cargo/rust environment variables.

Turns out this might be necessary for #[pg_test] tests that use std::env::var(...). When using --runas we spawn the postmaster with sudo, and its default policy is to reset the environment (env_reset flag in the sudoers file).

[eeeebbbbrrrr]

we're now doing the latter version:

$ FOO=bar sudo -u testuser printenv FOO
$ sudo -u testuser FOO=bar printenv FOO
bar

[workingjubilee]

this looks plausible but it seems like we could avoid most of this logic if we use sudo's flags more fully.

[workingjubilee]

hmm, regex maybe?

[workingjubilee]

if we use shlex, we should just skip the env vars that we can't quote the values of correctly, or we should panic more noisily, or we should stop iterating the env vars entirely. here is one of those options.

Suggested change

	let env_as_arg = format!("{var}={}", shlex::try_quote(&value)?);
	let Ok(quoted_val) = shlex::try_quote(&value) else {
	continue
	};
	let env_as_arg = format!("{var}={quoted_val}");

[workingjubilee]

alternatively, instead of splitting and then reapplying these, why not use sudo's --preserve-env=var,var,var,...? are we worried about not having the required privilege?

[eeeebbbbrrrr]

I didn’t see that in the man page. Let me investigate that and make sure we can rely on it even being there here in 2023.

[workingjubilee]

Needs a rebase, unforch.