Index Elements serialization. Structure view initial work

* WIP

Signed-off-by: aboyko <alex.boyko@broadcom.com>

* `SpringIndexElement` serialization. Initial Structure view in VSCode

Signed-off-by: aboyko <alex.boyko@broadcom.com>

* Corrections

Signed-off-by: aboyko <alex.boyko@broadcom.com>

* Serialization polishing

Signed-off-by: aboyko <alex.boyko@broadcom.com>

* Don't include java.lang.Object in supertypes serialization

Signed-off-by: aboyko <alex.boyko@broadcom.com>

---------

Signed-off-by: aboyko <alex.boyko@broadcom.com>

vscode-extensions/vscode-spring-boot/package.json

@@ -144,6 +144,10 @@
         }
       ],
       "commandPalette": [
+        {
+          "command": "vscode-spring-boot.structure.refresh",
+          "when": "false"
+        },
         {
           "command": "vscode-spring-boot.props-to-yaml",
           "when": "false"
@@ -184,6 +188,12 @@
       ]
     },
     "commands": [
+      {
+        "command": "vscode-spring-boot.structure.refresh",
+        "title": "Refresh",
+        "category": "Spring Boot",
+        "icon": "$(refresh)"
+      },
       {
         "command": "vscode-spring-boot.live-hover.connect",
         "title": "Show/Refresh/Hide Live Data from Spring Boot Processes",