Tethering: add isTetheringSupported with callerPkg parameter

BT tethering need to know whether tethering is supported for its caller
that call isTetheringSupported in binder thread under BT's process.
Current isTetheringSupported API is getting callerPkg inside
TetheringManager that would be BT's package name for bt tethering case.
Provide isTetheringSupported(String callerPkg) for caller to pass its
caller's package name if the use case is under binder IPC.

Bug: 146915889
Test: -boot, flash, boot
Change-Id: I2a35e1b6851e7a799c343be0dd60da23514768ba

Tethering/common/TetheringLib/src/android/net/TetheringManager.java

@@ -1131,6 +1131,25 @@ public class TetheringManager {
     public boolean isTetheringSupported() {
         final String callerPkg = mContext.getOpPackageName();
 
+        return isTetheringSupported(callerPkg);
+    }
+
+    /**
+     * Check if the device allows for tethering. It may be disabled via {@code ro.tether.denied}
+     * system property, Settings.TETHER_SUPPORTED or due to device configuration. This is useful
+     * for system components that query this API on behalf of an app. In particular, Bluetooth
+     * has @UnsupportedAppUsage calls that will let apps turn on bluetooth tethering if they have
+     * the right permissions, but such an app needs to know whether it can (permissions as well
+     * as support from the device) turn on tethering in the first place to show the appropriate UI.
+     *
+     * @param callerPkg The caller package name, if it is not matching the calling uid,
+     *       SecurityException would be thrown.
+     * @return a boolean - {@code true} indicating Tethering is supported.
+     * @hide
+     */
+    @SystemApi(client = MODULE_LIBRARIES)
+    public boolean isTetheringSupported(@NonNull final String callerPkg) {
+
         final RequestDispatcher dispatcher = new RequestDispatcher();
         final int ret = dispatcher.waitForResult((connector, listener) -> {
             try {