Sessions with auto-creation on fetch request and TTL (#736)

* Add support for sessions

* Add tests for sessions

* Missing return type

* Don't re-create an existing session

* Return success in case of session doesn't exists on destroy

* Create session if necessary on get request

* Add session TTL to the request.get method

When fetching some webpage with a predefined session id,
FlareSorverr is using existing instance of WebDriver.
That allows user to not manage cookies explicitly
and rely on WebDriver to maintain the session. However,
if session has been created long time ago, CloudFlare might
stop accepting the requests, so we want to recreate the session
time to time. From the user perspective the easiest way of doing it
is to define their expectation on the session duration.

These changes add an option to define Time-to-live (TTL) for the session
and FlareSorverr takes care about rotating the sessions.

* Update message for session destroy in tests

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Co-authored-by: Michel Roux <xefir@crystalyx.net>

src/dtos.py

@@ -33,6 +33,7 @@ class V1RequestBase(object):
     maxTimeout: int = None
     proxy: dict = None
     session: str = None
+    session_ttl_minutes: int = None
     headers: list = None  # deprecated v2.0.0, not used
     userAgent: str = None  # deprecated v2.0.0, not used