Include LICENSE in the generated jar under META-INF.

See google/guava#6468 and google/guava#6477.

I cowardly did not look into Auto and its many pom.xml files. And I gave up on jimfs when its jar didn't end up containing the license... maybe somehow related to how it has other files autogenerated into `META-INF`??

RELNOTES=n/a
PiperOrigin-RevId: 530613491

Author: cpovirk

pom.xml

@@ -92,6 +92,15 @@
   </dependencies>
 
   <build>
+    <resources>
+      <resource>
+        <directory>.</directory>
+        <includes>
+          <include>LICENSE.txt</include>
+        </includes>
+        <targetPath>META-INF</targetPath>
+      </resource>
+    </resources>
     <plugins>
       <plugin>
         <artifactId>maven-compiler-plugin</artifactId>