Extract lucky_avram and remove avram dependency

[matthewmcgarvey]

This is one of the last parts to making Avram optional in Lucky.
The code removed from here will be moved to avram luckyframework/avram#772
The moved code will be accessible to apps by adding additional requires and the lucky_cli change can be found here luckyframework/lucky_cli#711

This whole thing is a breaking change but in a minor way. Currently, having require "lucky" in your code pulled in all this code and also brought in avram. To get the same functionality, code will need to be updated to

require "lucky"
require "avram"
require "avram/lucky"

And then the tasks will also need to be imported in your tasks.cr file

require "avram/lucky/tasks"

[jwoertink]

Thanks for getting this started. I'm going to move forward with it now. This will allow people to use Lucky without a DB, or even use a different ORM if they'd like with a proper escape hatch. I think this will also make testing the lucky-avram bridge a lot easier with this code being closer to home.