ELECTRON: Import correct cloud file when multiple exist

[catloversg]

When retrieving Steam cloud data, we always use the first file returned from steamworksClient.cloud.listFiles. However, this API can return multiple files, and their order is not guaranteed.

MRE:

• Load save id "foo" on machine 1 and use "Delete Steam Cloud Data" option to ensure this save file is synced to Steam Cloud.
• Login Steam on machine 2 and let it sync "foo" to the remote folder.
• Use "Delete Steam Cloud Data" option again on machine 1 to sync another save id "bar" to Steam Cloud.
• After a while, Steam will sync "bar" to machine 2. Calling steamworksClient.cloud.listFiles on machine 2 now returns both "foo" and "bar" with no guaranteed order.

The fix is to use the most recently persisted cloud file instead of the first file in that array.

Note:

• In the case of having multiple cloud files, steamworksClient.cloud.writeFile always fails. This issue is tracked in BUGFIX: Electron app cannot sync new save file to Steam Cloud #2105. I'm holding off on that PR and wait for v3 release.
• There are many todo comments added in this PR. I can remove them if you want.

This PR uses a new version of my fork of steamworks.js.

• API: Check if a file is persisted in the Steam Cloud and get file timestamp ceifa/steamworks.js#207
• Transparency log entry: https://search.sigstore.dev/?logIndex=1133352212

[d0sboots]

I'm fine with the TODOs, I don't want to expand the scope of this beyond what it already is.