feat: Add welcome view when no folder opened (microsoft#1141)

package.json

@@ -71,8 +71,18 @@
         "viewsWelcome": [
             {
                 "view": "testExplorer",
-                "contents": "No test cases are listed because the Java Language Server is currently running in [LightWeight Mode](https://aka.ms/vscode-java-lightweight). To show test cases, click on the button to switch to Standard Mode.\n[Switch to Standard Mode](command:java.server.mode.switch?%5B%22Standard%22,true%5D)",
+                "contents": "%contributes.viewsWelcome.inLightWeightMode%",
                 "when": "java:serverMode == LightWeight"
+            },
+            {
+                "view": "testExplorer",
+                "contents": "%contributes.viewsWelcome.noProjectWithProjectManagerInstalled%",
+                "when": "workspaceFolderCount == 0 && java:projectManagerActivated && java:serverMode != LightWeight"
+            },
+            {
+                "view": "testExplorer",
+                "contents": "%contributes.viewsWelcome.noProjectWithOutProjectManagerInstalled%",
+                "when": "workspaceFolderCount == 0 && !java:projectManagerActivated && java:serverMode != LightWeight"
             }
         ],
         "menus": {

package.nls.json

@@ -31,5 +31,8 @@
     "configuration.java.test.config.vmArgs.description": "Specify the extra options and system properties for the JVM",
     "configuration.java.test.config.args.description": "Specify the command line arguments which will be passed to the test runner",
     "configuration.java.test.config.env.description": "Specify the extra environment variables when running the tests",
-    "configuration.java.test.config.sourcePaths.description": "Specify extra source paths when debugging the tests"
+    "configuration.java.test.config.sourcePaths.description": "Specify extra source paths when debugging the tests",
+    "contributes.viewsWelcome.inLightWeightMode": "No test cases are listed because the Java Language Server is currently running in [LightWeight Mode](https://aka.ms/vscode-java-lightweight). To show test cases, click on the button to switch to Standard Mode.\n[Switch to Standard Mode](command:java.server.mode.switch?%5B%22Standard%22,true%5D)",
+    "contributes.viewsWelcome.noProjectWithProjectManagerInstalled": "No folder opened in Visual Studio Code. You can [open a Java project](command:_java.project.open), or create a new Java project by clicking the button below.\n[Create Java Project](command:java.project.create)",
+    "contributes.viewsWelcome.noProjectWithOutProjectManagerInstalled": "No folder opened in Visual Studio Code."
 }

package.nls.zh.json

@@ -31,5 +31,8 @@
     "configuration.java.test.config.vmArgs.description": "设定启动 JVM 的额外选项和系统属性",
     "configuration.java.test.config.args.description": "设定启动 Test Runner 时的命令行参数",
     "configuration.java.test.config.env.description": "启动应用程序时自定义的环境变量",
-    "configuration.java.test.config.sourcePaths.description": "设定调试测试用例时的源代码路径"
+    "configuration.java.test.config.sourcePaths.description": "设定调试测试用例时的源代码路径",
+    "contributes.viewsWelcome.inLightWeightMode": "由于 Java 语言服务正运行在 [LightWeight 模式](https://aka.ms/vscode-java-lightweight)下，因此测试用例将不会展示在该视图中。如果您需要展示测试用例，可以点击下方按钮将 Java 语言服务切换至 Standard 模式。\n[切换至 Standard 模式](command:java.server.mode.switch?%5B%22Standard%22,true%5D)",
+    "contributes.viewsWelcome.noProjectWithProjectManagerInstalled": "当前没有已打开的文件夹，您可以[打开一个 Java 项目](command:_java.project.open)，或点击下方按钮创建一个新的 Java 项目。\n[创建 Java 项目](command:java.project.create)",
+    "contributes.viewsWelcome.noProjectWithOutProjectManagerInstalled": "当前没有已打开的文件夹。"
 }