[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 is more suitable for agones. Subsystem exists from GameInstance initialization and will proceed to exist during all server lifetime.
  • Subsystem not being part of actor, which is part of the world, would not be destroyed during level change.
  • Subsystem owns its own timer manager, which also would not be affected by world.
  • Subsystem would be created only for server builds by default. That behavior easily changeable since its just virtual func. ShouldCreateSubsystem().

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

• Added bDisableAutoHealthPing to disable auto call to HealthPing() during init

• Added blueprint readonly flag support for HealthRateSeconds, bDisableAutoHealthPing, bDisableAutoConnect so controlling subsystem calls from BPs would be easier.

• Added static Get() of subsystem, so it would be easily obtained from anywhere you have a context object.

• 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.

[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