[WIP] 1.2 Test Split - Modules own tests

[jaxwilko]

@LukeTowers told me to...

This PR splits out tests into their related modules, allowing for each module to be targeted using the winter:test command. Added to this is also proper namespacing and a bunch of minor bug fixes and tweaks.

[bennothommo]

Hey guys, 2 thoughts on this -

• Are we going to be forcing everyone to have to add use System\Tests\Bootstrap\PluginTestCase to their plugin test cases? I think we should probably still have that available as a global alias if possible.
• With the tests directories within the modules, we may have to look into using a .gitattributes file on each module with export-ignore definitions so that the tests aren't included on each install through Composer. (see Support for unsetting export-ignore attribute in .gitattributes composer/composer#9153 and https://github.com/laravel/framework/blob/9.x/.gitattributes#L9-L23)

[LukeTowers]

@bennothommo

1. Yes, we are. Any existing projects will still have the original tests folder and they can keep using that if they want.
2. I want the tests folders for the modules distributed via Composer, that way the winter:test command can always be used and our testing suite can stay up to date with the rest of the platform. Right now if we make any changes to the testing suite or the base classes the only way users can get those changes is by manually downloading them to update their project tests folder.

[bennothommo]

@bennothommo

1. Yes, we are. Any existing projects will still have the original tests folder and they can keep using that if they want.

As long as that doesn't create any conflicts, all good!

2. I want the tests folders for the modules distributed via Composer, that way the `winter:test` command can always be used and our testing suite can stay up to date with the rest of the platform. Right now if we make any changes to the testing suite or the base classes the only way users can get those changes is by manually downloading them to update their project tests folder.

I suppose it will be handy to not have to instruct people to download or updates their test folders anymore.

[jaxwilko]

Removed global func/const imports in d1ff094