220 - Fix: Filters disappear when the filters results is 1 file

[MellyGray]

What this PR does / why we need it:

This PR fixes an incorrect behaviour that hides the filters and search bar when the filters results in just 1 file.

The expected behaviour is that after using the filters, if the result is just 1 file, you still can see and use the filters and search bar.

Which issue(s) this PR closes:

• Closes Fix - Bug when filtering on files tab and there is only one result file #220

Special notes for your reviewer:

Suggestions on how to test this:

Step 1: Run the development environment

1. Run npm I
2. cd packages/design-system && npm run build
3. cd ../../
4. Check that you have a .env file such as the .env.example, with the VITE_DATAVERSE_BACKEND_URL=http://localhost:8000 variable
5. cd dev-env
6. ./run-env.sh unstable
7. To check the environment go to http://localhost:8000 and check your local dataverse installation

Step 2: Test Dataset View mode

1. Go to http://localhost:8000
2. Login as admin using username: dataverseAdmin and password: admin1
3. Create a new Dataset and add different type of files.
4. From the dataset view mode copy the search parameters from the url. Ex.: ?persistentId=doi:10.5072/FK2/LHGRHP&version=DRAFT
5. Go to http://localhost:8000/spa/datasets and paste the search parameters. Ex.: http://localhost:8000/spa/datasets?persistentId=doi:10.5072/FK2/LHGRHP&version=DRAFT
6. You are seeing now the same Dataset in the SPA. Use the filters to show just 1 result and check that the filters are still available so you can use them to again show All the files

Does this PR introduce a user interface change? If mockups are available, please link/include them here:

No

Is there a release notes update needed for this change?:

No

Additional documentation:

Video from the incorrect behaviour:

[GPortas]

@MellyGray Please can you resolve the conflicts?

[coveralls]

coverage: 98.278% (-0.01%) from 98.29%
when pulling 240a4fc on fix/220-filtering-on-files-tab-and-there-is-only-one-file
into 1acebdf on develop.

[MellyGray]

@GPortas conflicts resolved

[GPortas]

Works as expected!