Fix settings file array parsing when no commas are present

[rjmholt]

PR Summary

Fixes #1160.

The settings parsing logic didn't automatically capture arrays where elements are separated by newline.

I've fix that in the parser and added some tests to make sure it stays fixed.

PR Checklist

• PR has a meaningful title
  • Use the present tense and imperative mood when describing your changes
• Summarized changes
• Change is not breaking
• Make sure all .cs, .ps1 and .psm1 files have the correct copyright header
• Make sure you've added a new test if existing tests do not effectively test the code changed and/or updated documentation
• This PR is ready to merge and is not Work in Progress.
  • If the PR is work in progress, please add the prefix WIP: to the beginning of the title and remove the prefix when the PR is ready.

[bergmeister]

Looks good to me with only a minor/optional style improvement suggestion.

[rjmholt]

Noticed this was missing and quickly added it. Makes sense from a layering perspective -- null should be parse-able but might not be allowed as a configurable value.

[bergmeister]

What about just simplifying the whole code to bool.tryparse ?

[rjmholt]

If one of the possibilities is null, then it would probably look like:

string varName = varExprAst.VariablePath.UserPath.ToLower();
if (bool.TryParse(varName, out bool val))
{
    return val;
}

if (varName == "null")
{
    return null;
}

throw CreateInvalidDataExceptionFromAst(varExprAst);

I'm not sure that's simpler though -- the switch/case has a nice flow to me, and ideally the C# compiler knows better than I do about how to make it work quickly. (Although it looks like that's not the case, since I would implement a trie for optimum speed).