GobalCTB iframe dynamic sizing

[wpalani]

Proposed changes

Issue: Some GlobaCTBs are not rendering well withing the modal because they require larger width/height. Since the module can't know or calculate the content of the iframe, it will rely on the source to communicate that information.
More info about this issue: https://jira.newfold.com/browse/PRESS1-406

The source may send a postMessage with type: frameWidth, when the value is received, we'll set the iframe width to that value. Then, the parent can ask the source/iframe to calculate the height and send another postMessage with height value.

We're also refactoring the tests to make them slightly more granular.

Demo

ctb_dynamic-size.mp4

Type of Change

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Checklist

• I have read the CONTRIBUTING doc
• Linting and tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

Internal Ticket: https://jira.newfold.com/browse/PRESS1-406