.vscode: add more settings, extensions.

.vscode/extensions.json

+{
+  "recommendations": [
+    "kaiwood.endwise",
+    "misogi.ruby-rubocop",
+    "rebornix.ruby",
+    "wingrunr21.vscode-ruby"
+  ]
+}

.vscode/settings.json

 {
-    "ruby.rubocop.executePath": "/usr/local/Homebrew/Library/Homebrew/shims/gems/"
-}
\ No newline at end of file
+    "ruby.rubocop.executePath": "Library/Homebrew/shims/gems/",
+    "files.trimTrailingWhitespace": true,
+    "editor.tabSize": 2,
+    "files.insertFinalNewline": true,
+}