cal-101-caldav-integration (#419)

* add generic calendar icon for caldav

* module for symmetric encrypt/decrypt

* caldav integration

* use Radix dialog

* Move caldav components to /caldav

* remove duplicate cancel button, unused function

* ensure app can connect to caldav server before adding

* fix calendar clients can possibly return null

* fix: add caldav dialog does not close when submitted

* safely attempt all caldav operations

* clarify variable name, fix typo

* use common helper for stripping html

* remove usage of request lib until "completed"

* add types and usage comments to crypto lib

* add encryption key to example env file

.env.example

@@ -34,3 +34,7 @@ EMAIL_SERVER_USER='<office365_emailAddress>'
 EMAIL_SERVER_PASSWORD='<office365_password>'
 # ApiKey for cronjobs
 CRON_API_KEY='0cc0e6c35519bba620c9360cfe3e68d0'
+
+# Application Key for symmetric encryption and decryption
+# must be 32 bytes for AES256 encryption algorithm
+CALENDSO_ENCRYPTION_KEY=