Java IDE: minor improvements

[molly-moen]

A few style/accessibility improvements to the java ide:

• add labels to the console and editor inputs
• add a header to the console
• fix gruntfile import for css file

Only visible change to the editor is the addition of the header to the console (and removal of the border that was previously around the console):

Testing story

Tested locally. The Java IDE is only available for admins and levelbuilders currently.

Reviewer Checklist:

• Tests provide adequate coverage
• Privacy and Security impacts have been assessed
• Code is well-commented
• New features are translatable or updates will not break translations
• Relevant documentation has been added or updated
• User impact is well-understood and desirable
• Pull Request is labeled appropriately
• Follow-up work items (including potential tech debt) are tracked and linked

[jmkulwik]

One typo nit. Other than that, LGTM!