common/Scripts: add check_update function to helper.sh

[joebonrichie]

Summary

• for quick anitya monitoring of a single package

Test Plan

source script in environment and run check_update on a bunch of packages

Checklist

• Package was built and tested against unstable

[davidjharder]

How much of a pain is it to write fish and zsh versions?

Seems there is no good way to call a bash function from within the fish shell

[silkeh]

How much of a pain is it to write fish and zsh versions?
Seems there is no good way to call a bash function from within the fish shell

I'd make it a separate script instead and call that from all three helper functions.

[ermo]

The code in itself is sound.

However, it would be way more useful if the actual logic was made into a standalone script, which is then called from the various helper scripts via a function.

Do you have any appetite for doing this rewrite?

[malfisya]

With ent landing in repository, wouldn't that supersede this PR?