Add XML documentation for Android.Net.IpSec.Ike

The `Android.Net.IpSec.Ike` namespace contains **627** `To be added` placeholders in source XML documentation (excluding `docs\xml\index.xml`).

Example command:

```powershell
rg -n -i --glob 'Android.Net.IpSec.Ike/**' --glob 'ns-Android.Net.IpSec.Ike.xml' 'to be added' docs\xml
```

## Update log

- 2026-09-10: Refreshed the placeholder scan from **625** to **627** (increased by **2**). Related documentation PRs: [#644](https://github.com/dotnet/android-api-docs/pull/644).

Start by running the provided rg command against docs\xml to enumerate the 627 `To be added` placeholders under Android.Net.IpSec.Ike, excluding docs\xml\index.xml. Read the matching XML documentation files and replace the placeholders with accurate API descriptions. Done means no `To be added` placeholders remain in the namespace scan.

Vom Indexierungsmodell aus dem Issue-Text verfasst.