Collections Page - Create new content from within a collection

[jmakowski1123]

When users are on a Collection Page, one option to populate the Collection with content is to create new content within the collection.

Option 1: Create new content

When a user clicks on the "new" button, this triggers the "Add content" sidebar to open.
Users can select to create a new text, problem, video block.
NOTE: Creating a new unit is out of scope for the MVP.
When a content type is selected, the requisite editor opens, which will be addressed in Epic 4. For now, the Add Content sidebar just needs to exist.
After the content has been edited in the Editor, the content tile automatically populates in the Collection Page. If the Collections page is in the auto-sorted state, which is "recently modified" by default, then the new content tile will appear first. If the Collections page has another sort applied, then the new content tile will appear accordingly, and the page should jump to the new tile's location.

[navinkarkera]

@jmakowski1123 @lizc577 @sdaitzman @marcotuts This is ready for AC testing on the sandbox

[jmakowski1123]

When I click "edit" on a text or a problem block that is in a collection, and then I click save, I am bumped out of the Collection and back to Library Home. The expected behavior should be: If I edit a piece of content from within a collection, then I should stay in the collection after clicking "save".

[bradenmacdonald]

When I click "edit" on a text or a problem block that is in a collection, and then I click save, I am bumped out of the Collection and back to Library Home. The expected behavior should be: If I edit a piece of content from within a collection, then I should stay in the collection after clicking "save".

@jmakowski1123 that will be fixed by #1321 which I should get to soon.