Improve goimpl implememtations (golang#1547)

* change InputBox to QuickPick
* search workspace interface symbol according to keyword
* change static code text to code snippet

Author: day-dreams

.vscode/launch.json

@@ -20,14 +20,14 @@
 				"--disable-extensions"
 			],
 			"outFiles": [
-                "${workspaceFolder}/dist/**/*.js"
-            ],
+				"${workspaceFolder}/dist/**/*.js"
+			],
 			"stopOnEntry": false,
 			"sourceMaps": true,
 			"smartStep": true,
 			"preLaunchTask": "npm: webpack",
 			"env": {
-				"VSCODE_GO_IN_TEST": ""  // Enable code
+				"VSCODE_GO_IN_TEST": "" // Enable code
 			},
 		},
 		{
@@ -61,7 +61,7 @@
 				"999999"
 			],
 			"env": {
-				"VSCODE_GO_IN_TEST": "1"  // Disable code that shouldn't be used in test
+				"VSCODE_GO_IN_TEST": "1" // Disable code that shouldn't be used in test
 			},
 			"stopOnEntry": false,
 			"sourceMaps": true,
@@ -83,10 +83,11 @@
 				"--extensionDevelopmentPath=${workspaceFolder}",
 				"--extensionTestsPath=${workspaceFolder}/out/test/gopls/index",
 				"--user-data-dir=${workspaceFolder}/.user-data-dir-test",
-				"--timeout", "999999",
+				"--timeout",
+				"999999",
 			],
 			"env": {
-				"VSCODE_GO_IN_TEST": "1"  // Disable code that shouldn't be used in test
+				"VSCODE_GO_IN_TEST": "1" // Disable code that shouldn't be used in test
 			},
 			"stopOnEntry": false,
 			"sourceMaps": true,
@@ -122,4 +123,4 @@
 			]
 		}
 	]
-}
+}