Implement Search bar

[DrStrangeloovee]

Continuation of #16.

The search bar should serve as a helpful utility for finding any text in the available notes of the user. Obviously there is back end logic to implement to query the database for the search parameter. Additionally a place to display the search results is needed. This feature needs more refinement in separate issues.

Note - I found a simple implementation for a full-text-search with pocketbase maybe this becomes useful in the future:
pocketbase/pocketbase#3807

[DrStrangeloovee]

May be discarded as the app could be seen as feature complete without this one. If there is time for it somebody could grab it. Based of the current master branch there shouldn't be anything holding us back from starting with this one - if there is time for it...