Release Islandora IIIF as stand alone Drupal module

[Natkeeran]

Similar to Islandora Openseadragon, it would be helpful to release Islandora IIIF as a stand alone Drupal module. This may provide additional visibility and use outside of Islandora.

Work involved is relatively minor.

1. Remove the islandora dependency - https://github.com/Islandora/islandora/blob/8.x-1.x/modules/islandora_iiif/islandora_iiif.info.yml#L8
2. Provide documentation to create this view : https://github.com/Islandora/islandora_defaults/blob/8.x-1.x/config/install/views.view.iiif_manifest.yml

Current installation should be able to uninstall the submodule and install this module, then setup the view again!

[seth-shaw-unlv]

We can also drop that view config into the new module's config/optional/ directory which will auto-create it if all the dependencies are met.

[kspurgin]

suggested module name: iiif_view_manifest (tech meeting 2021-06-23)