share: add prefix/param for shared field in location hash

Right now the shared fields are displayed and added to the location like:
`http://localhost/#root$item_pkd44k$item_dprmi9`

It is better to:
- [ ] add prefix (e.g. `shared_field` => `http://localhost/#shared_field=root$item_pkd44k$item_dprmi9` ).
>>> this way we can allow for multiple functions of the location hash (e.g. if an app already utilizes hash locations, our functionality can be added on top, etc)
- [ ] maybe support for multiple selections?