Adding support for custom activity type

[PixelHir]

Discord Rich Presence now supports activities other than just „Playing”. Support for those could be potentially implemented into this library as well?
discordjs/RPC#149

[Lachee]

Yup i will be adding this over the weekend. Advaith pinged me to be aware.

[Hazzz895]

Yup i will be adding this over the weekend. Advaith pinged me to be aware.

when