Add ObjectForm

[haojianzong]

• Project Name: ObjectForm
• Project URL: https://github.com/haojianzong/ObjectForm
• Project Description: A simple yet powerful library to build form for your class models.
• Why it should be added to awesome-swift:
• At least 15 stars (GitHub project)
• Support Swift 5
• Updated contents.json instead of README
• Lib is fully open sourced, written in Swift and not a wrapper over compiled lib
• Description does not say "written in Swift" or variant 🤓

[vpeschenkov]

Thank you, @haojianzong!