patch site object in cms has siteobject with defaultProjection in response

[floriangantner]

Describe the bug
The site object is usually returned in allLanguages Projection.

dspace-angular/src/app/core/data/site-data.service.ts

Line 51 in 30543a4

const searchParams: RequestParam[] = [new RequestParam('projection', 'allLanguages')];

Using the cms metadata component to edit the site object returns some patch(ed) Object with the default projection.

dspace-angular/src/app/admin/edit-cms-metadata/edit-cms-metadata.component.ts

Line 78 in 30543a4

this.site = restResponse.payload;

To Reproduce
Steps to reproduce the behavior:

1. define and configure some cms in two languages (e.g. en,de)

2. Edit both of the entries and save.
   

3. You are returned to the dropdown of selected cms metadata.
   

4. visit entry again

5. the entry in the none-main language (=de) should be empty
   

6. Administers which might click the save button loose the previously saved data.

Expected behavior
We expect the site object to be returned correctly with all languages or to be reloaded after the change

Related work
Link to any related tickets or PRs here.