Add XML documentation for Android.Hardware.Camera2.Params

The `Android.Hardware.Camera2.Params` namespace contains **331** `To be added` placeholders in source XML documentation (excluding `docs\xml\index.xml`).

Example command:

```powershell
rg -n -i --glob 'Android.Hardware.Camera2.Params/**' --glob 'ns-Android.Hardware.Camera2.Params.xml' 'to be added' docs\xml
```

## Update log

- 2026-09-10: Refreshed the placeholder scan from **327** to **331** (increased by **4**). Related documentation PRs: [#644](https://github.com/dotnet/android-api-docs/pull/644).

Start with the PowerShell rg command in the issue to locate the 331 "To be added" placeholders under docs\xml for Android.Hardware.Camera2.Params, excluding docs\xml\index.xml. Read the surrounding XML entries to determine the documentation scope for each item. Done means all 331 placeholders in this namespace have meaningful XML documentation and the scan no longer finds them.

Written by the indexing model from the issue text.