make classes final

[jrushlow]

• replaces the annotated @final with PHP final keyword. Which in turn cleans up our tests a wee-bit..

As a side effect of that, we need to be able to mock ResetPasswordRandomGenerator, ResetPasswordTokenGenerator, & ResetPasswordCleaner. Which you cannot do when using the final keyword.

One work around would be to use something like https://github.com/dg/bypass-finals. This approach is cool, but it's more or less a "one size fits all" approach. Part of our tests guarantee that we are not using final classes where we shouldnt. So instead of "flaky" tests, I went with...

Implementing interface's for the classes we need to mock. I'm usually the first to say NO when it comes to adding to the public API that will increase our maintenance burden / technical debt. But, I think having these interfaces will be beneficial in the long run.

a) We sort of tease that hey, you can create your own ResetPasswordHelper by implementing the ResetPasswordHelperInterface. But as you dig deeper down the rabbit hole, you quickly find out that you can't actually do that. Mostly because our generators, models, and utils are final xor internal (As they should be). Swapping out the concrete argument and return types with the interfaces allows developers to truly implement their own customized implementations without needing us to change our own implementations in the bundle.

and

b) should there be better, more secure, less problematic, etc. methods of doing say, generateToken(), providing an interface will take some of the pressure off of us to push out a fix while trying to preserve BC. Atleast, thats the goal.

Todo:

• update tests that mock these classes
• update this PR text to include the interfaces that we're adding (assuming we press forward with this)
• document changes in the upgrade log (I'm sure someone out there is using these in userland) 👀
• flesh out the new interfaces