Date/Time string formats

### What's the Problem?

When dealing with date or time objects, it is very common to translate that object into a readable string. For example, "09:35:10" or "08/04/2022 - 12:02". However, sometimes doing this is error-prone, like the difference between "dd.MM.yyyy" and "dd.mm.yyyy" in Java's DateTimeFormatter.

### Solution/Idea

A UI that let's the user input a date format (using dropdowns and/or buttons) which converts that into a string that is used for formatting time in common languages, like C# and Java.

### Alternatives

Another option would be letting the user select a language (if needed), then letting him input a string a seeing what would be printed for the current date (today).

### Priorities

| Capability | Priority |
| :---------- | :------- |
| This proposal will allow developers to accomplish W | Must |
| This proposal will allow end users to accomplish X | Should |
| This proposal will allow developers to accomplish Y | Could |
| This proposal will allow end users to accomplish Z | Won't |

### DevToys Version

_No response_

### Comments

_No response_

The issue names no files, tests, or entry points. Start by reviewing DevToys’ existing tool structure and clarifying the supported date-format languages and UI scope; done means an agreed design and a working formatter workflow for the requested examples.

Written by the indexing model from the issue text.