* refactor: Move http client into provider
* refactor: Rework ollama provider for work with internal http client
* refactor: Rework LM Studio provider to work with internal http client
* refactor: Rework Mistral AI to work with internal http client
* fix: Replace url and header to QNetworkRequest
* refactor: Rework Google provider to use internal http client
* refactor: OpenAI compatible providers switch to use internal http client
* fix: Remove m_requestHandler from tests
* refactor: Remove old handleData method
* fix: Remove LLMClientInterfaceTest
chore: Add unit tests for DocumentContextReader
The tests are based on GTest like some tests in Qt Creator itself, which
makes it easy to run as full Qt Creator does not need to be started.
