5.1 - Restore command helper tests and add BannerHelper

[markstory]

When adding BannerHelper I noticed that we were missing test cases for the other helpers. It seems like the files were removed during 5.x, I have to assume during one of the many very large merge conflicts. I've restored those tests now.

These changes also contain a new console helper for emitting banners. With my terminal theme the following code

$styles = ['info.bg', 'warning.bg', 'error.bg', 'success.bg'];
$helper = new BannerHelper(new ConsoleIo());
$helper->withPadding(5);
foreach ($styles as $style) {
    $helper
        ->withStyle($style)
        ->output(['All done!']);

}

Emits the following.

I would appreciate any other results, as I'm not sure I have the colors right.

[othercorey]

A bright color for info would look like a result to me. Could we try grey with cyan text?

[markstory]

We don't have grey right now, as we only do the basic 8 color ansi palette. We could use white as the background, or not include a banner style for info 🤷

[othercorey]

White would work.

[othercorey]

We are always assuming utf-8 for multi-byte encoding, right?

[markstory]

Yeah, if folks need a non-utf8 encoding they'll have to configure the global encoding.

[othercorey]

Right. What I meant was we're injecting ascii characters into an mb stream, so we can only support utf8 output.

[othercorey]

Just realized this is only for console. I don't think consoles support anything incompatible with ascii space.