Un-hardcode officer names

- Use site preferences for officer names

- There is no way update the names directly besides using the following line while debugging the app:

    ```
    quip.apps.getSitePreferences().save({officers: {
        president: 'President',
        vpm: 'Vice President of Membership',
        vpe: 'Vice President of Education',
        vppr: 'Vice President of Public Relations',
        secretary: 'Secretary',
        soa: 'Sergeant of Arms',
        treasurer: 'Treasurer',
    }})
    ```

Fixes #12.

Author: mxxk

app/manifest.json

@@ -3,8 +3,8 @@
     "manifest_version": 4,
     "name": "Toastmasters Agenda",
     "disable_app_level_comments": false,
-    "version_name": "2.1.2",
-    "version_number": 21,
+    "version_name": "2.1.3",
+    "version_number": 22,
     "sizing_mode": "fill_container",
     "initial_height": 300,
     "initial_width": 300,

src/utils/print-and-save.js

@@ -88,17 +88,7 @@ function getPrintAgendaData() {
         data: {
             date:
                 getRichTextRecordContent(rootRecord.get('date').get('value')),
-            // TODO (#12): Use site preferences to store officer names instead
-            //     of hard-coding.
-            officers: {
-                president: 'KC Lakshminarasimham',
-                vpm: 'Anny He',
-                vpe: 'Srinath Krishna Ananthakrishnan',
-                vppr: 'Max Kukartsev',
-                secretary: 'Rosaura Arevalo',
-                soa: 'Jack Faraday',
-                treasurer: 'Ron Sison',
-            },
+            officers: quip.apps.getSitePreferences().getForKey('officers'),
             items,
         },
     };