Fold provisioning + detection into one single-flight SiteProvisioningSource

Promotes the EditorCapabilityDetector into SiteProvisioningSource: one
per-site, single-flight pipeline that ensures application-password
credentials, recovers the REST root, and detects editor capabilities —
each stage awaited before the next. Because the capability probe is now
structurally downstream of credential provisioning, it can never run
before the mint, so the first-login race is gone by construction rather
than mitigated. The application-password card, connectivity banner, and
editor preloader all render slices of the one SiteReadiness state.

The mint/validate mechanics move out of ApplicationPasswordViewModelSlice
(now a renderer) into the source's ensureAuth stage; the per-site
single-flight subsumes the card's old 409-safety guard. The duplicate
wpApiRestUrl heal collapses into the source's recoverRestUrl stage.

Author: jkmassel

WordPress/src/main/java/org/wordpress/android/AppInitializer.kt

@@ -71,7 +71,7 @@ import org.wordpress.android.networking.ConnectionChangeReceiver
 import org.wordpress.android.networking.OAuthAuthenticator
 import org.wordpress.android.networking.RestClientUtils
 import org.wordpress.android.push.GCMRegistrationScheduler
-import org.wordpress.android.repositories.EditorCapabilityDetector
+import org.wordpress.android.repositories.SiteProvisioningSource
 import org.wordpress.android.support.ZendeskHelper
 import org.wordpress.android.ui.ActivityId
 import org.wordpress.android.ui.debug.cookies.DebugCookieManager
@@ -231,7 +231,7 @@ class AppInitializer @Inject constructor(
     lateinit var wpApiClientProvider: WpApiClientProvider
 
     @Inject
-    lateinit var editorCapabilityDetector: EditorCapabilityDetector
+    lateinit var siteProvisioningSource: SiteProvisioningSource
 
     @Inject
     lateinit var openWebLinksWithJetpackHelper: DeepLinkOpenWebLinksWithJetpackHelper
@@ -722,8 +722,8 @@ class AppInitializer @Inject constructor(
         wpServiceProvider.clearAll()
         wpApiClientProvider.clearAllClients()
 
-        // Drop per-site editor-capability detection state for the signed-out user
-        editorCapabilityDetector.clear()
+        // Drop per-site provisioning + capability state for the signed-out user
+        siteProvisioningSource.clear()
     }
 
     /*