Add Event to Player Capacity update

[markmandel]

What type of PR is this?

Uncomment only one /kind <> line, hit 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

What this PR does / Why we need it:

Useful for an audit trail on your GameServer

Looks like I missed this on initial implementation.

Which issue(s) this PR fixes:

Work on #1033

Special notes for your reviewer:

None.

[agones-bot]

Build Succeeded 👏

Build Id: 5ed5c884-7201-40a0-b115-e66e008b4764

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

• image: gcr.io/agones-images/agones-controller:1.6.0-a22c4d0
• image: gcr.io/agones-images/agones-sdk:1.6.0-a22c4d0
• image: gcr.io/agones-images/agones-ping:1.6.0-a22c4d0
• Linux C++ SDK (build): agonessdk-1.6.0-a22c4d0-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.6.0-a22c4d0.zip

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

• https://a22c4d0-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/GoogleCloudPlatform/agones.git pull/1497/head:pr_1497 && git checkout pr_1497
• helm install ./install/helm/agones --namespace agones-system --name agones --set agones.image.tag=1.6.0-a22c4d0

[agones-bot]

Build Succeeded 👏

Build Id: c9729714-0e60-4800-b5a4-a10597f491e0

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

• image: gcr.io/agones-images/agones-controller:1.6.0-7f150b8
• image: gcr.io/agones-images/agones-sdk:1.6.0-7f150b8
• image: gcr.io/agones-images/agones-ping:1.6.0-7f150b8
• Linux C++ SDK (build): agonessdk-1.6.0-7f150b8-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.6.0-7f150b8.zip

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

• https://7f150b8-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/GoogleCloudPlatform/agones.git pull/1497/head:pr_1497 && git checkout pr_1497
• helm install ./install/helm/agones --namespace agones-system --name agones --set agones.image.tag=1.6.0-7f150b8

[aLekSer]

More logging and events is better.

[google-oss-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aLekSer, markmandel

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• OWNERS [markmandel]

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