Cleanup, more CI testing for scripts, validate inputs

[stertooy]

• Turn more steps into separate scripts that are now tested in CI (see Split out some of the more complex steps into separate files and add tests #27)
• Move all scripts to a folder.
• Replace GAP Error by Exec("echo \"::error:: [...] \""); FORCE_QUIT_GAP(1); to make the errors more visible in GitHub Action logs.
• Validate inputs when relevant (like in run-pkg-tests).
• Made indendation consistent (2 spaces per level).

[limakzi]

This file is a GAP "script", I mean, we can easily treat it as script with GAP as execution environment, but in general I'm not a big fan of including Actions logic into GAP.

Writing an abstraction layer could be helpful.

@fingolfin What do you think?

[fingolfin]

I guess we could have a file gh_actions.g which contains code that re-defines Error to do something else (e.g. call Exec like here), and then change e.g.

gap -A -q $GITHUB_ACTION_PATH/scripts/pkginfo_to_json.g

to

gap -A -q $GITHUB_ACTION_PATH/scripts/gh_actions.g $GITHUB_ACTION_PATH/scripts/pkginfo_to_json.g

But I am not sure it's worth the trouble? After all, you can run pkginfo_to_json.g locally even with that Exec for errors in it.

[fingolfin]

I.e. I am not sure what another abstraction layer would gain us, what benefit it would bring? Its downside is the usual: it adds complexity and thus opportunity for new bugs, and makes debugging harder.

(I am not saying there are no issues, just that I don't see them; happy to learn)

[fingolfin]

Doesn't GitHub run scripts with set -e anyway? Then we could just do this, and get better info about which check failed:

Suggested change

	if ! ./check_date.sh "$(date +%Y-%m-%d)" \
	|| ! ./check_date.sh "$(date -d "1 day ago" +%Y-%m-%d)" \
	|| ! ./check_date.sh "$(date -d "1 day" +%Y-%m-%d)" \
	|| ./check_date.sh "$(date -d "2 days ago" +%Y-%m-%d)" \
	|| ./check_date.sh "$(date -d "2 days" +%Y-%m-%d)"
	then
	exit 1
	fi
	! ./check_date.sh "$(date +%Y-%m-%d)"
	! ./check_date.sh "$(date -d "1 day ago" +%Y-%m-%d)"
	! ./check_date.sh "$(date -d "1 day" +%Y-%m-%d)"
	./check_date.sh "$(date -d "2 days ago" +%Y-%m-%d)"
	./check_date.sh "$(date -d "2 days" +%Y-%m-%d)"

[limakzi]

@fingolfin I prefer your syntax.
I think GitHub does, but its for testing, I suppose.

[fingolfin]

I am in favor of merging this (and tagging it so it gets use) rather sooner than later.