Search box in the overview page behaves not as expected

[RubenFricke]

Describe the bug
The search bar on the overview page doesn't work as expected. Whenever I search for a correct part of a project it finds the project, but whenever I add or remove some (correct) letters, it doesn't find the project anymore.

Besides that, whenever I search with a certain query and it finds a set of projects, it doesn't matter what categories I select. Even though non of the projects have the selected category, it still returns all the categories.

To Reproduce

1. Open the backend with a fresh seeded database
2. Open the Search endpoint in swagger
3. Query: unbranded
4. Validate that it finds 3 projects

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5. Query: unbrande
6. Validate that it finds no projects

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5. Query: unbranded, category: 1
6. Validate that it still finds all the 3 projects even though they don't have the selected category.

Expected behavior
Improve the search mechanism that avoids the named bugs above and include the selected categories in the filtering of projects.

Screenshots

Additional context
Probably same issue reported here: DigitalExcellence/dex-frontend#537

Category filter problem has also been mentioned in this pull request: DigitalExcellence/dex-frontend#524

[RubenFricke]

Forgot the close in this pull request: #479