Unreal CountsAndLists SDK implementation

[igooch]

Arbitrary Counters and Lists for GameServers, SDKs and Allocation #2716 has been released in Alpha, and is looking for a contributor with Unreal experience to implement the Unreal SDK. The SDK methods to implement are listed in #2716, and have been implemented in Go https://github.com/googleforgames/agones/blob/main/sdks/go/alpha.go:

• func (a *Alpha) GetCounterCount(key string) (int64, error)
• func (a *Alpha) IncrementCounter(key string, amount int64) (error)
• func (a *Alpha) DecrementCounter(key string, amount int64) (error)
• func (a *Alpha) SetCounterCount(key string, amount int64) (error)
• func (a *Alpha) GetCounterCapacity(key string) (int64, error)
• func (a *Alpha) SetCounterCapacity(key string, amount int64) (error)
• func (a *Alpha) GetListCapacity(key string) (int64, error)
• func (a *Alpha) SetListCapacity(key string, amount int64) (error)
• func (a *Alpha) ListContains(key, value string) (bool, error)
• func (a *Alpha) GetListLength(key string) (int, error)
• func (a *Alpha) GetListValues(key string) ([]string, error)
• func (a *Alpha) AppendListValue(key, value string) (error)
• func (a *Alpha) DeleteListValue(key, value string) (error)

The Unreal SDK should be implemented in the https://github.com/googleforgames/agones/tree/main/sdks/unreal/Agones directory.

The Go proto is https://github.com/googleforgames/agones/blob/main/proto/sdk/alpha/alpha.proto. Note that the proto methods do not exactly match the above listed SDK methods. This is due to the difference between the design in #2716 and the Google AIP https://google.aip.dev/general guidance that the proto follows as closely as possible.

Due to licensing issues we don’t have a way to do unit or conformance testing for Unreal as part of the CI/CD pipeline. Please make sure that this SDK is as well tested as possible.

[igooch]

@KiaArmani @Titantompa we're looking for contributors with Unreal experience if you or someone on your teams have the time to take this on.