[Feature Enhancement]: Unify and Improve `@DateFormatting`

[MasterJ93]

Summary

Create a solution where the @DateFormatting property wrapper is able to handle all of the requirements without the need to create custom implementations.

Pain points

At this time, there are two property wrappers: @DateFormatting and DateFormattingOptional. While their current implementations work, there are a couple of issues:

• Having one for Date and another for Date? can be a little bit confusing and can possibly lead to situations where bugs can occur.
• The initializers currently have an unconventional way of being initialized, where the property must begin with an underscore before the name of the variable.
• The decoding and encoding methods must be implemented.

A solution is needed to fix the latter two, while the first issue can be solved by merging @DateFormatting and @DateFormattingOptional into one, unified @DateFormatting property wrapper.

Considered Alternatives

No response

Is this a breaking change?

No

Library Examples

No response

Additional Context

The tasks include:

• [ ] Add the @DateFormattingOptional-related implementations into @DateFormatting.
• [ ] Tweak the code so the standard initializer is no longer needed to be initialized.
• [ ] Tweak the code so that creating a customized decoding method is no longer required.
• [ ] Tweak the code so that creating a customized encoding method is no longer required.