Move existing UWB API classes to UWB apex

Following instructions from go/mainline-java-lib to move the existing
UWB API classes to the new apex.

Bug: 194906542
Test: Compiles
Change-Id: I08801b418c7ba42c76952f5a80745cd0057ca329
diff --git a/boot/Android.bp b/boot/Android.bp
index b71f9bf..049c802 100644
--- a/boot/Android.bp
+++ b/boot/Android.bp
@@ -100,6 +100,10 @@
             module: "com.android.tethering-bootclasspath-fragment",
         },
         {
+            apex: "com.android.uwb",
+            module: "com.android.uwb-bootclasspath-fragment",
+        },
+        {
             apex: "com.android.wifi",
             module: "com.android.wifi-bootclasspath-fragment",
         },