Add example for writing a FileFormat

[alamb]

Is your feature request related to a problem or challenge?

Now that @devinjdangelo has added better support for user defined file formats (see #11060)

We have an example of a custom table provider: https://datafusion.apache.org/library-user-guide/custom-table-providers.html and example

It would be great to have an example of creating a file format

Such an example would make sure the APIs added in this PR can be used for the end to end case, as well as obviously made it easier for others to discover and use this feature

Describe the solution you'd like

Add an example in https://github.com/apache/datafusion/tree/main/datafusion-examples that does:

1. Creates a new file format (something basic like use CSV / ROT13)
2. reads / writes data using that format

Describe alternatives you've considered

No response

Additional context

No response

[tshauck]

take

[tshauck]

I'll take this as I want to try it out. I do this for one of my libraries via the parser plus user defined nodes, so I want to see what this looks like as an alternative.

[alamb]

I'll take this as I want to try it out. I do this for one of my libraries via the parser plus user defined nodes, so I want to see what this looks like as an alternative.

Thanks @tshauck -- note #11060 isn't merged yet, so you may have to start the example against that branch rather than main

[alamb]

#11060 is now merged 🎉