Create downloadable lemminx-maven uber JAR

Issue: eclipse#430

lemminx-maven/pom.xml

@@ -197,7 +197,9 @@
 				<configuration>
 					<descriptors>
 						<descriptor>src/assembly/deps.xml</descriptor>
+						<descriptor>src/assembly/uber.xml</descriptor>
 					</descriptors>
+					<finalName>${project.artifactId}</finalName>
 				</configuration>
 				<executions>
 					<execution>
@@ -207,6 +209,13 @@
 							<goal>single</goal>
 						</goals>
 					</execution>
+					<execution>
+						<id>uber-jar</id> <!-- this is used for inheritance merges -->
+						<phase>package</phase> <!-- bind to the packaging phase -->
+						<goals>
+							<goal>single</goal>
+						</goals>
+					</execution>
 				</executions>
 			</plugin>
 		</plugins>

lemminx-maven/src/assembly/uber.xml

@@ -0,0 +1,25 @@
+<assembly xmlns="http://maven.apache.org/ASSEMBLY/2.0.0"
+  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xsi:schemaLocation="http://maven.apache.org/ASSEMBLY/2.0.0 http://maven.apache.org/xsd/assembly-2.0.0.xsd">
+  <!-- 
+  Copied from jar-with-dependencies because we want to both control the local name 
+  AND attach the binary to the project build artifacts. Workaround for https://issues.apache.org/jira/browse/MASSEMBLY-824
+   -->
+  <id>uber</id>
+  <formats>
+    <format>jar</format>
+  </formats>
+  <includeBaseDirectory>false</includeBaseDirectory>
+  <dependencySets>
+    <dependencySet>
+      <outputDirectory>/</outputDirectory>
+      <useProjectArtifact>true</useProjectArtifact>
+      <unpack>true</unpack>
+      <scope>runtime</scope>
+      <excludes>
+      	<exclude>org.eclipse.lemminx:org.eclipse.lemminx:*</exclude>
+      	<exclude>org.eclipse.lsp4j:*:*</exclude>
+      </excludes>
+    </dependencySet>
+  </dependencySets>
+</assembly>