Make adding the new build field not mandatory

Also adds a helper function that reads the property when it exists using reflection

WooCommerce/src/main/kotlin/com/woocommerce/android/ui/login/LoginActivity.kt

@@ -56,6 +56,7 @@ import com.woocommerce.android.util.ChromeCustomTabUtils
 import com.woocommerce.android.util.ChromeCustomTabUtils.Height.Partial.ThreeQuarters
 import com.woocommerce.android.util.UrlUtils
 import com.woocommerce.android.util.WooLog
+import com.woocommerce.android.util.getBuildConfigValueOrNull
 import dagger.android.AndroidInjector
 import dagger.android.DispatchingAndroidInjector
 import dagger.android.HasAndroidInjector
@@ -351,7 +352,8 @@ class LoginActivity :
         clearCachedSites()
 
         if (authOptions != null) {
-            val forcePasswordLogin = BuildConfig.DEBUG && BuildConfig.FORCE_PASSWORD_LOGIN
+            val forcePasswordLogin = BuildConfig.DEBUG &&
+                getBuildConfigValueOrNull<Boolean>("FORCE_PASSWORD_LOGIN") == true
 
             if (authOptions.isPasswordless && !forcePasswordLogin) {
                 showMagicLinkRequestScreen(email, verifyEmail, allowPassword = false, forceRequestAtStart = true)

WooCommerce/src/main/kotlin/com/woocommerce/android/util/BuildConfigExt.kt

@@ -0,0 +1,13 @@
+package com.woocommerce.android.util
+
+import com.woocommerce.android.BuildConfig
+
+@Suppress("SwallowedException")
+inline fun <reified T> getBuildConfigValueOrNull(key: String): T? {
+    return try {
+        val field = BuildConfig::class.java.getField(key)
+        field.get(null) as? T
+    } catch (e: NoSuchFileException) {
+        null
+    }
+}