Feature Request: Option to define allowed conversions

[Estradamis]

So far ConvertX is a nice self hosted converting solution, Kudos to dev team. For the use case sharing it with others, it would be nice if some formats can be either whitelisted, so that only those can be used or I can generally configure available conversions as I do not want to offer all of them (eg. Picture only or heic <-> jpeg). This could go along with using weak hardware where I would assume converting a video might take lots of resources compared to simple Text to PDF or image conversion

[C4illin]

What do you think about just limiting compute time instead? Like #146