Implement the missing methods of the bson.ArrayConstructor type and add tests for each method. The methods should set the key to be "0", the bson.Array type will handle updating this value to the correct index.

The remaining methods are:

• Double
• String
• Document
• Array
• Binary
• ObjectID
• Boolean
• DateTime
• Null
• Regex
• DBPointer
• Javascript
• Symbol
• CodeWithScope
• Int32
• Uint64
• Int64
• Decimal128
• MinKey
• MaxKey