feat: basic collection editor

[evanstoner]

Introduces a bare bones CollectionEditor component.

• Supports loading, saving, and deleting collection objects as JSON
• Alerts provide success, error, and informational tips based on collection API responses
• Caller determines whether collection name and object name are editable, and whether to automatically load a value on render
• Caller can provide default object value if not found in the collection
• Caller can disable load, save, and delete buttons as necessary

Closes #3