Added the Self Serve Data Model (#367)

* added recursion and inition decorators

* working version

* added todo comment and removed console.log

* Added Recursive add

* removed type requirement

* proper resolution of promises

* added custom element and base class

* Made selfServe standalone page

* Added custom renderer as async type

* Added overall defaults

* added inital open from data explorer

* removed landingpage

* added feature for self serve type

* renamed sqlx->example and added invalid type

* Added comments for Example

* removed unnecessary changes

* Resolved PR comments

Added tests
Moved onSubmt and initialize inside base class
Moved testExplorer to separate folder
made fields of SelfServe Class non static

* fixed lint errors

* fixed compilation errors

* Removed reactbinding changes

* renamed dropdown -> choice

* Added SelfServeComponent

* Addressed PR comments

* merged master

* added selfservetype.none for emulator and hosted experience

* fixed formatting errors

* Removed "any" type

* undid package.json changes

package.json

@@ -8,6 +8,8 @@
     "@azure/cosmos": "3.9.0",
     "@azure/cosmos-language-service": "0.0.5",
     "@azure/identity": "1.2.1",
+    "@babel/plugin-proposal-class-properties": "7.12.1",
+    "@babel/plugin-proposal-decorators": "7.12.12",
     "@jupyterlab/services": "6.0.0-rc.2",
     "@jupyterlab/terminal": "3.0.0-rc.2",
     "@microsoft/applicationinsights-web": "2.5.9",
@@ -87,6 +89,7 @@
     "react-notification-system": "0.2.17",
     "react-redux": "7.1.3",
     "redux": "4.0.4",
+    "reflect-metadata": "0.1.13",
     "rx-jupyter": "5.5.12",
     "rxjs": "6.6.3",
     "styled-components": "4.3.2",