Add Migrations middleware

[dereuromark]

Resolves #317

We could check on a query string skip-migration-check = 1 and if so, also behave like non debug mode.
This can be useful if you need to check something prior to actually running it locally.

[dereuromark]

Open tasks

• Make connection table more dynamic (and get default one from connection manager)
• Make phinxlog table more dynamic
• tests
• 'app' false/true to only allow plugins to be checked (e.g. if you are working alone, and only want to check vendor plugins)

[LordSimal]

I can think of plugins which do contain migrations which I don't want/need to run in my app because I just use parts of that plugin (e.g. this one).
Therefore it would be good to ignore either a whole plugin from this logic or specific migrations.

[dereuromark]

Therefore it would be good to ignore either a whole plugin from this logic or specific migrations.

The plugins list is already opt-in by default, so if you dont specify a plugin it would not run the check on it.
If you skip specific migrations, that is out of scope here.

[dereuromark]

It works now for app and plugins, you can provide a list of plugins, otherwise only app.
You can provide a different connection string, otherwise defaults to default.

Anything else? Or does this only need tests etc to get finished up?

Also removed some dead dormant code that wasnt been used for a while.

[dereuromark]

I might need a bit of help with the tests, also because they seem to leak to stdout

[dereuromark]

Ideas that could also be done as part of a follow up PR

• 'cache' false/true to allow caching based on the hashsum of all migration files (app+plugin), this would then safe a bit of queries maybe? on the other side this needs still the file lookups.

[dereuromark]

@markstory

1) Migrations\Test\TestCase\Middleware\PendingMigrationsMiddlewareTest::testAppMigrationsSuccess
TypeError: Migrations\Db\Adapter\MysqlAdapter::quoteTableName(): Argument #1 ($tableName) must be 
of type string, null given, called in 
/home/runner/work/migrations/migrations/src/Db/Adapter/MysqlAdapter.php on line 110

Can we relax this code not to require the name if not given?
It seems to work fine for other adapters.
Or do we need to fix this up? If so, I wonder how to make the tableName not null.

//EDIT
Actually, I think there is sth weird in the way the Manager is delegating that info.
But I managed to fix up the tests.

[dereuromark]

@markstory The tests leaking some stdout output in console still seems to be there.
I wonder if we can somehow silence this for the middleware?

[markstory]

In other tests those leaks were caused by new output objects being created instead of using stubs.