Allow custom css to be injected

[hamzahsn]

Currently, we're using this library to generate notification our own notification, but the issue is that we're not able to add some custom styling such as positioning, we know that currently there INotyfPosition which allow us to provide something like the following:

position: {
    x: 'right',
    y: 'top',
  }

Where as you can see I'm only allowed to provide description of the positioning.

Desired behavior:

I would be able to provide a custom positioning eg:

position: {
  x: 'right 10px',
  y: 'top 50px'
 }

or even something similar.

Right now we are overriding the class name notyf in order to be able to get this feature, but would love to have such kind of dynamic positioning, I didn't find in the documentation such kind of thing, so would be great to have it if that's possible.

PS: very nice lib, we love it 😍

[razafinarivohanania]

@hamzahsn I need this feature too. For my case, i need to custom z-index of the notification.