Add XML documentation for Java.Lang.Invoke

The `Java.Lang.Invoke` namespace contains **430** `To be added` placeholders in source XML documentation (excluding `docs\xml\index.xml`).

```powershell
rg -n -i --glob 'Java.Lang.Invoke/**' --glob 'ns-Java.Lang.Invoke.xml' 'to be added' docs\xml
```

## Update log

- 2026-09-10: Refreshed the placeholder scan from **496** to **430** (reduced by **66**). Related documentation PRs: [#408](https://github.com/dotnet/android-api-docs/pull/408), [#441](https://github.com/dotnet/android-api-docs/pull/441), [#476](https://github.com/dotnet/android-api-docs/pull/476), [#500](https://github.com/dotnet/android-api-docs/pull/500), [#552](https://github.com/dotnet/android-api-docs/pull/552), [#644](https://github.com/dotnet/android-api-docs/pull/644).

Start by running the provided rg command from the repository root to inspect the 430 remaining placeholders under docs\xml for Java.Lang.Invoke, excluding docs\xml\index.xml. Read the matching ns-Java.Lang.Invoke.xml and Java.Lang.Invoke/** entries to understand the affected API members. Done means the namespace's 430 reported "To be added" placeholders have useful XML documentation and the scan no longer reports them.

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