fix: default primp mobile requests to GaiResolver

[ndonkoHenri]

Fixes the primp mobile recipe so ordinary Android HTTPS requests no longer abort natively on first use.

Resolves flet-dev/flet#6603

Cause

primp is built with the hickory-dns feature enabled. In primp-reqwest, that makes Hickory the default DNS resolver when the caller does not provide one.

On Android, Hickory’s system DNS configuration path calls into ndk-context to access the Android Context. Flet loads primp as a Python extension through serious_python, and that Rust Android context is not initialized there. As a result, the first network request can abort the process with:

android context was not initialized

This happens below Python, so the app can crash before a Python exception can be raised or caught.

Fix

The recipe patch now changes the Python binding’s client builder behavior for mobile builds:

• if the user passes an explicit dns_resolver, keep using that resolver
• otherwise, on Android/iOS, install GaiResolver as the default resolver

This routes normal hostname resolution through the platform getaddrinfo path and avoids Hickory’s Android ndk-context system-DNS path. Explicit DoH/DoT/plain resolver support remains available.

The recipe test now performs a real HTTPS request and asserts that the request path either completes or raises a Python-level request error, rather than aborting the process.