Merge pull request #5478 from k9mail/user_installed_CAs

Add network security config to allow user-installed CAs

app/k9mail/src/main/AndroidManifest.xml

@@ -45,6 +45,7 @@
         android:name="com.fsck.k9.App"
         android:allowTaskReparenting="false"
         android:usesCleartextTraffic="true"
+        android:networkSecurityConfig="@xml/network_security_config"
         android:icon="@drawable/ic_launcher"
         android:label="@string/app_name"
         android:theme="@style/Theme.K9.Startup"

app/k9mail/src/main/res/xml/network_security_config.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<network-security-config xmlns:tools="http://schemas.android.com/tools"
+    tools:ignore="InsecureBaseConfiguration,AcceptsUserCertificates">
+
+    <base-config cleartextTrafficPermitted="true">
+        <trust-anchors>
+            <certificates src="system" />
+            <certificates src="user" />
+        </trust-anchors>
+    </base-config>
+
+</network-security-config>