printf support for datetime, categorical, etc

[apjanke]

In Matlab, you can pass datetime, categorical, and related arrays to '%s' conversion specifiers, and it works. Update Tablicious to do this.

[apjanke]

Could pull in the dispstr API to do this, but I don't know if that's a good idea, since Tablicious' goal is to eventually be accepted into core Octave, and dispstr is not standard Matlab functionality.

[PratyushD35]

@apjanke I am a beginner and wanted to contribute. Can you guide me to solve the issue?

[apjanke]

Hi, Pratyush!

I'm afraid I can't: I'm still not entirely sure how this feature should work, and I'm still thinking through its design and behavior in my head. In particular, I don't know if I should introduce dispstr-API-related stuff, and I'm not sure how nonscalar arrays should convert in this context.