Engine V7: `get_evaluation_result` interface

[khvn26]

Blocked by Flagsmith/flagsmith#5808.

In order to improve coupling/cohesion and simplify later Evaluation Context extensions:

1. Retire/deprecate the following interfaces:

• get_environment_flags
• get_environment_flag
• get_identity_flags
• get_identity_flag
• evaluate_identity_in_segment/is_context_in_segment
• get_identity_segments/get_context_segment

2. Implement a single get_evaluation_result(context: EvaluationContext) -> EvaluationResult interface, returning the following information:

• List of evaluated flags with corresponding values.
• List of segments that include the provided context.

Note that we'll need to extend the Evaluation object with:

• Environment features
• Segments

[gagantrivedi]

Feels a bit odd that a function named get_flags returns anything other than flags(i.e: segments in this case)

[khvn26]

Renamed to get_evaluation_result.