Bug/several small UI fixes

[dukeofharen]

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

Issue Number: N/A

What is the new behavior?

• When editing a stub and pressing tab, insert spaces instead of actual tab.
• Added simple editor for editing stub because editing a very large stub might cause codemirror to crash.
• Added separate text box for tenant and scenario form helpers.

Does this introduce a breaking change?

• Yes
• No

Other information