Cleanup license metadata in external/rust/crates/fragile.

Add package and license module in Android.bp. File LICENSE is from upstream project, so use it in Android.bp.

Bug: 346390141
Change-Id: Id4e2cd4309078d383d4b3b2b15c2022dcb9395ed
Test: CIs
diff --git a/Android.bp b/Android.bp
index c833fee..58c6e71 100644
--- a/Android.bp
+++ b/Android.bp
@@ -5,6 +5,18 @@
 
 package {
     default_team: "trendy_team_android_rust",
+    default_applicable_licenses: ["external_rust_crates_fragile_license"],
+}
+
+license {
+    name: "external_rust_crates_fragile_license",
+    visibility: [":__subpackages__"],
+    license_kinds: [
+        "SPDX-license-identifier-Apache-2.0",
+    ],
+    license_text: [
+        "LICENSE",
+    ],
 }
 
 rust_test {