Close dialogs on history back

[bramkragten]

Proposed change

A start on closing dialogs on history back like we already did for the more info dialog.

Extra bonus, going forward in the browser history will reopen the dialog (if possible).
If you open a dialog from another dialog, going back from the second dialog will reopen the first dialog.

Dialogs should implement a closeDialog function, that should take care of closing the dialog and then fire the event dialog-closed.

You can prevent a dialog from closing on back by returning false from closeDialog (for a dialog that should not be closed without a specific action of that doesn't have a cancel/close button).

Dialogs that don't implement closeDialog yet, won't be closed on back, and the history will be a little screwed up (first back will not do anything, second back will give the current behavior).
So we should add closeDialog to all dialogs 😄

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (thank you!)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example configuration

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io