feat(wilbur): add /health endpoint for load balancer routing

[rclarke87]

Returns 200 when no player is connected, 503 when one is. Allows an
Azure load balancer health probe to remove busy servers from the pool.

Relevant components:

• Signalling server
• Common library
• Frontend library
• Frontend UI library
• Matchmaker
• Platform scripts
• SFU

Problem statement:

What problem does this PR address?

Solution

How does this PR solve the problem?

Documentation

If you added a new feature or changed an existing feature please add some documentation here.

Or better yet, link to the relevant /Docs update in your PR.

Test Plan and Compatibility

What steps have you taken to ensure this PR maintains compataibility with the existing functionality?

Or better yet, link to the unit tests that accompany this PR.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 9309c4b

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[rclarke87]

sorry, didn't mean to create a PR on official