[Unreal] Refactor agones component to subsystem

[GloryOfNight]

What type of PR is this?

Uncomment only one /kind <> line, press enter to put that in a new line, and remove leading whitespace from that line:

/kind breaking

/kind bug
/kind cleanup

/kind documentation

/kind feature

/kind hotfix
/kind release

What this PR does / Why we need it:

• Refactor agones from using ActorComponent to GameInstanceSubsystem:

  • Subsystem seems to be more suitable for agones in general. Documentation on topic
  • Subsystem will persist across all worlds.
  • Subsystem easier to integrate, since it does not require being part of some actor which it should be attached to. You can see updated documentation to understand how much easier it to use.
  • Subsystem would be created only for server builds, saving on resources.
  • Subsystem could be easily obtained using Get() function from any UObject context

• Removed final keyword, to allow basing of Subsystem and overriding it's behavior.

• Added bDisableAutoHealthPing variable to disable auto call to HealthPing() during Initialization

• Added blueprint readwrite flag support for HealthRateSeconds, bDisableAutoHealthPing, bDisableAutoConnect to improve blueprint support slightly.

• Space&Tabs mix change to just Tabs

Special notes for your reviewer:

That is something we used internally for some time already and I think people can benefit from that change.
This change would break code that was previously dependent on AgonesComponent.

build.log

[agones-bot]

Build Succeeded 🥳

Build Id: 3ab0bc2c-9618-471a-af73-0f58076bc7d9

The following development artifacts have been built, and will exist for the next 30 days:

• image: us-docker.pkg.dev/agones-images/ci/agones-controller:1.45.0-dev-0d0c4d4
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.45.0-dev-0d0c4d4
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.45.0-dev-0d0c4d4-linux
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.45.0-dev-0d0c4d4
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.45.0-dev-0d0c4d4
• Linux C++ SDK (build): agonessdk-1.45.0-dev-0d0c4d4-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.45.0-dev-0d0c4d4.zip

A preview of the website (the last 30 builds are retained):

• https://0d0c4d4-dot-preview-dot-agones-images.appspot.com/

To install this version:

git fetch https://github.com/googleforgames/agones.git pull/4033/head:pr_4033 && git checkout pr_4033
helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.45.0-dev-0d0c4d4

[agones-bot]

Build Failed 😭

Build Id: 25d7e15e-cdf9-4b3c-a2b3-6d160f0177d3

Status: FAILURE

• Cloud Build view
• Cloud Build log download

To get permission to view the Cloud Build view, join the agones-discuss Google Group.

[gongmax]

/gcbrun

[agones-bot]

Build Succeeded 🥳

Build Id: f3e2be54-b83b-4fda-ae32-fdb1375a3cc7

The following development artifacts have been built, and will exist for the next 30 days:

• image: us-docker.pkg.dev/agones-images/ci/agones-controller:1.45.0-dev-b87eaef
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.45.0-dev-b87eaef
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.45.0-dev-b87eaef-linux
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.45.0-dev-b87eaef
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.45.0-dev-b87eaef
• Linux C++ SDK (build): agonessdk-1.45.0-dev-b87eaef-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.45.0-dev-b87eaef.zip

A preview of the website (the last 30 builds are retained):

• https://b87eaef-dot-preview-dot-agones-images.appspot.com/

To install this version:

git fetch https://github.com/googleforgames/agones.git pull/4033/head:pr_4033 && git checkout pr_4033
helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.45.0-dev-b87eaef