Run tests with Gradle instead of IDEA's test runner

IDEA's test runner doesn't work very well with multi-module projects,
particularly where there are different versions of jars in the
classpath.

Signed-off-by: Graham <gpe@openrs2.dev>

.idea/runConfigurations/dev_openrs2.xml

@@ -1,16 +0,0 @@
-<component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="dev.openrs2" type="JUnit" factoryName="JUnit">
-    <option name="PACKAGE_NAME" value="dev.openrs2" />
-    <option name="MAIN_CLASS_NAME" value="" />
-    <option name="METHOD_NAME" value="" />
-    <option name="TEST_OBJECT" value="package" />
-    <option name="VM_PARAMETERS" value="-ea -Dio.netty.leakDetection.level=PARANOID" />
-    <option name="PARAMETERS" value="" />
-    <option name="TEST_SEARCH_SCOPE">
-      <value defaultName="wholeProject" />
-    </option>
-    <method v="2">
-      <option name="Make" enabled="true" />
-    </method>
-  </configuration>
-</component>

.idea/runConfigurations/test.xml

@@ -0,0 +1,22 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="test" type="GradleRunConfiguration" factoryName="Gradle">
+    <ExternalSystemSettings>
+      <option name="executionName" />
+      <option name="externalProjectPath" value="$PROJECT_DIR$" />
+      <option name="externalSystemIdString" value="GRADLE" />
+      <option name="scriptParameters" value="" />
+      <option name="taskDescriptions">
+        <list />
+      </option>
+      <option name="taskNames">
+        <list>
+          <option value="cleanTest" />
+          <option value="test" />
+        </list>
+      </option>
+      <option name="vmOptions" value="" />
+    </ExternalSystemSettings>
+    <GradleScriptDebugEnabled>true</GradleScriptDebugEnabled>
+    <method v="2" />
+  </configuration>
+</component>