Search engine

## Description
Implementation of the [E04](https://github.com/akai-org/put-wiki/blob/13-fill-out-documentation/docs/product/requirements.md#e04-wyszukiwarka-informacji) functional requirement from docs. This refers also to general navigation in the app. Students should be able to find information they want quickly.

## Scope
### What is included:
- Flat content hierarchy. Flat list of courses with search, sorting, filtering (similar to ecommerce) is easier to find and read than this deep hierarchy: department -> field of study -> study degree -> study mode -> course (like on ekursy/put poznan).
- Simple, well structured header (with menu) and footer in the app.
- _(optional)_ Defining user flows from the start (what they might want to find) through how to search that info (every step in the app) to success (sequence diagrams).

### Out of scope:
- Search engine with autocomplete (hard technically, not so useful at the beginning of the project - no/little data for searching)

## Related user stories (that an epic consists of)
- #ID
- #ID

## Notes
Important context