Add build-test-pkgs and extra-pkgs inputs

[stertooy]

The first input is as suggested in a Slack conversation.

The second input, well, I'm not sure if it's needed - ideally everything would be covered by the other inputs, But it probably doesn't hurt to have either.

[stertooy]

Converting this to draft. Ideally this will be built on top of #22.

[fingolfin]

This code is now repeated for the 4th time. How about factoring the bulk out into a helper function AddDeps (better name welcome), which might be called as, say,

Suggested change

	if ( IsBound( info.Dependencies.TestPackages ) and (
	"${{ inputs.build-test-pkgs }}" = "recursive" or
	( "${{ inputs.build-test-pkgs }}" = "true" and depth = 1 )
	)) then
	for pkg in info.Dependencies.TestPackages do
	name := LowercaseString( pkg[1] );
	Print( " - is tested using package '", name, "'\n" );
	if not name in done then
	AddSet( todo, name );
	fi;
	od;
	fi;
	AddDeps( "TestPackages", "${{ inputs.build-test-pkgs }}", "is tested using package" );

and that helper might look roughly like this (untested, and indentation ought to be fixed):

Suggested change

	if ( IsBound( info.Dependencies.TestPackages ) and (
	"${{ inputs.build-test-pkgs }}" = "recursive" or
	( "${{ inputs.build-test-pkgs }}" = "true" and depth = 1 )
	)) then
	for pkg in info.Dependencies.TestPackages do
	name := LowercaseString( pkg[1] );
	Print( " - is tested using package '", name, "'\n" );
	if not name in done then
	AddSet( todo, name );
	fi;
	od;
	fi;
	AddDeps := function(field, mode, desc)
	if ( IsBound( info.Dependencies.(field) ) and (
	mode = "recursive" or
	( mode = "true" and depth = 1 )
	)) then
	for pkg in info.Dependencies.(field) do
	name := LowercaseString( pkg[1] );
	Print( " - ", desc, " '", name, "'\n" );
	if not name in done then
	AddSet( todo, name );
	fi;
	od;
	fi;
	end;