Consolidate Visualization container, avoid using default iframe

[guerler]

Currently Visualizations are displayed in the generic Galaxy main iframe, this requires manually setting the globally available iframes source attribute from another component, and hide the router-view. This PR adds a Visualization specific container which will allow navigating to Visualizations using router.push. This is a requirement for a more resilient visualization creation and displaying mechanism.

How to test the changes?

(Select all options that apply)

• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. [add testing steps and prerequisites here if you didn't write automated tests covering all your changes]

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.