Configure WV HAL APEX to be updatable

- add "supportRebootless" to apex_manifest.json
- add <allowed-vendor-apex> sysconfig
- add "on property:apex.com.google.android.widevine.ready=true" to .rc

Now, we can test `adb install` new version of the APEX and see the
service is restarted from the new version.

Note that this doesn't mean that DRM Framework works fine with the
update.

Bug: 248192031
Test: adb install --force-non-staged \
   -i com.android.vending \
   $OUT/vendor/com.google.android.widevine.apex
Change-Id: I7c41b224f0bb55742c0023c23196bba4a09e555f

libwvdrmengine/apex/Android.bp

@@ -58,6 +58,11 @@ apex {
     key: "com.google.android.widevine.key",
     certificate: ":com.google.android.widevine.certificate",
     updatable: false,
+
+    // install sysconfig to allow the apex to be updatable
+    required: [
+        "allowlist_com.google.android.widevine.xml",
+    ],
 }
 
 linker_config {
@@ -81,3 +86,10 @@ prebuilt_etc {
     name: "com.google.android.widevine.rc",
     src: "com.google.android.widevine.rc",
 }
+
+prebuilt_etc {
+    name: "allowlist_com.google.android.widevine.xml",
+    src: "allowlist_com.google.android.widevine.xml",
+    vendor: true,
+    sub_dir: "sysconfig",
+}