Log warnings to the console

[leonvogt]

Warnings added:

• data-controller doesn't match any registered controller
• Turbo Frame ID is not unique
• Elements with data-turbo-permanent but no id (or no unique id)
• Stimulus targets that aren't nested within the corresponding controller
• Stimulus values that aren't defined on the controller element but instead on child element
• Stimulus outlet selector is defined but does not match any elements on the page

[leonvogt]

The last two warning were not added because I'm currently unsure how to approach them.
The data attributes for values and and outlets are dynamic:

• data-[identifier]-[outlet]-outlet=
• data-[identifier]-[value]-value=

This extension has currently no information about the possible values or outlets, defined in the controllers.
Since I didn't find a good regex style of querying the DOM, to find the right data-attributes, it seems quite difficult to spot wrong placement or content for these.

The only good option I see, would be to extract the possibles values and outlets from the window.Stimulus object.
With that it would be a lot easier to query the right data attributes.

But I would like to tackle that in a different PR, since I feel like it would be handy to grab more than just the values and targets from the window object.