Make create post available

[Equasa]

Before this can be done #16 needs to be done!

We want to be able to create posts from our website so create a form for this (see EventsForm.tsx). All the appropriate information should be able to be edited.

1. Create the form and fix so that there is a button for this on the post page.
2. Add the appropriate formfields where you take in data
3. Make the post route using mutate (see EventsForm.tsx) OBS: don't forget const queryClient = useQueryClient(); in your application. Otherwise it won't work.