changes made for further search (fulltextsearch support)

[aslsumen]

Add further search feature for android app

This pull request implements a new feature that allows users to search
for files that contain a given word in the android app. Previously, the
search function only returned files that matched the word exactly, which
was not very useful for finding relevant documents.

The new feature uses the fulltextsearch service of nextcloud to perform
a more advanced query on the files. It requires the installation of some
provider apps that extract content from the files and index them using
Elasticsearch, a Java-based search engine.

The code changes include creating a new method to perform the search
request, parsing the response as a JSON object, and displaying the
results in a recycler view. The code also handles the possible errors
and exceptions that might occur during the network request.

This feature improves the user experience and makes the app more
functional and convenient. It also aligns with the nextcloud philosophy
of providing a unified and secure platform for data and communication.

[github-actions]

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