app: Small load time performance improvements

[illume]

Some small performance improvements for app loading.

• app: Fix to not use sync when getting bundledPlugins dir
• app: Fix isWSL check to be async
• app: Fix isWSL to do a cheap platform check first
• app: Make loadZoomFactor async and avoid modifying zoom if not needed
• app: Fix build manifest loading to be async

Testing

• Zoom persistence still works (change app zoom, restart app)
• Build app and check that plugin catalog is still there

Benchmarks

This was timed with video, excluding the first load. I expect this to work faster with a cold cache... because a lot of these changes are avoiding blocking when there's IO.

• Surface book 3 WSL compiled app(linux_unpacked), to see clusters: 6.5 seconds → 4.0 seconds — 1.6x faster
• Surface book 3 Windows compiled app, to see clusters: 4.7 seconds → 3.8 seconds — 1.2x faster
• Macbook Air M4 compiled app, to see clusters: 1.5 seconds → 1.6 seconds — 1.1x slower

For mac the initial window and frontend loads faster... but initially shows no cluster data, then the cluster data comes in. So I think there's a separate fix needed in the frontend.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: illume

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [illume]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment