feat(bluetooth): Initial nRF52 BSIM based test support.

Co-authored-by: Cem Aksoylar <caksoylar@users.noreply.github.com>

app/boards/native_posix_64.overlay

@@ -4,6 +4,7 @@
 
 / {
     chosen {
+        zephyr,console = &uart0;
         zmk,kscan = &kscan;
     };
 
@@ -15,4 +16,13 @@
         columns = <2>;
         exit-after;
     };
+
+    uart0: uart {
+        status = "okay";
+        compatible = "zephyr,native-posix-uart";
+        /* Dummy current-speed entry to comply with serial
+         * DTS binding
+         */
+        current-speed = <0>;
+    };
 };