vsx-registry: fix the search query based on the search parameters

[vince-fugnitto]

What it does

The following pull-request fixes the open-vsx search query which was previously incorrectly built when providing multiple search parameters.

• fixes the search query to support multiple search parameters.
• adds unit tests for the building of the search query.
• adds support for additional search parameters (sortBy, sortOrder, and includeAllVersions).

How to test

• the CI should successfully pass (build and test of the newly added unit test file).
• the functionality should work as before:
  • start the application, and navigate to the extensions view
  • search for an extension (it should yield results like on master)

Review checklist

• as an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• as a reviewer, I agree to behave in accordance with the review guidelines

Signed-off-by: vince-fugnitto [email protected]

[paul-marechal]

LGTM, thanks!