AI Structure Manager

**Describe the feature**
This feature will introduce an Structure Manager for the FAF default AI. Its goal is to allow the centralized means for the AI to upgrade structures without using the builders or the platoon former manager. It will allow different AI personalities to have different upgrade personalities and change its game play style in regards to upgrading structures.

It will consist of a new class called 'StructureManager'. The class will be self contained and will be created during the AI's skirmish system initialization. It will use the AI personality string to configure default values for various preferences and changes to upgrade behavior.

**First Implementation**
The first use case for the StructureManager will be mass extractor upgrades. The manager will handle all mass extractor upgrades for the AI. It will maintain data on the extractor metrics such as counts and the number of extractors currently upgrading. It will contain logic for extractor upgrades that can be manipulated depending on the AI personality. All logic will cover existing builder conditions.
The manager 'may' manage upgrades task based on economy metrics (e.g pausing upgrades if the AI goes into a power stall etc) depending on testing results.

This manager is currently in development and will be seeking feedback from both code developers and experienced players to assist in framework and logic design at the time of the pull request.

Future implementations into the Structure Manager will include.
Factory Upgrading
Shield Upgrading
Radar Upgrading

any other structure upgrade functions that are currently housed within the platoon former manager.

**Additional context**
Information on personality configurations.
The idea is that different AI personalities will have different preferences for mass extractor upgrade investment default values.
e.g
A rush AI may only dedicate 25% of income to mass upgrades where a turtle AI may dedicate 40%.
A rush AI may be more prone to pause extractor upgrades than a turtle AI.