Switch images to svgs, where possible (#1563)

Closes #1361, #1362

_includes/sections/calendar-contacts-sync.html

@@ -7,7 +7,7 @@
 {%
   include cardv2.html
   title="Nextcloud"
-  image="/assets/img/provider/Nextcloud.png"
+  image="/assets/img/svg/3rd-party/nextcloud.svg"
   description="<strong>Nextcloud</strong> is a suite of client-server software for creating and using file hosting services. This includes calendar sync via CalDAV and contacts sync via CardDAV. Nextcloud is free and open-source, thereby allowing anyone to install and operate it without charge on a private server."
   website="https://nextcloud.com/"
   forum="https://forum.privacytools.io/t/discussion-nextcloud-calender-contacts-sync-tools/1535"
@@ -25,7 +25,7 @@
 {%
   include cardv2.html
   title="EteSync"
-  image="/assets/img/provider/etesync.png"
+  image="/assets/img/svg/3rd-party/etesync.svg"
   description="<strong>EteSync</strong> is a secure, end-to-end encrypted, and privacy-respecting cloud backup and synchronization software for your personal information (e.g. contacts and calendars). There are native clients for Android, iOS, and the web, and an adapter layer for most desktop clients. It costs $24 per year to use, or you can host the server yourself for free."
   website="https://www.etesync.com/"
   forum="https://forum.privacytools.io/t/discussion-etesync-calender-contacts-sync-tools/1536"
@@ -45,7 +45,7 @@
 {%
   include cardv2.html
   title="Email Providers"
-  image="/assets/img/misc/email.png"
+  image="/assets/img/svg/layout/email.svg"
   description='Many email providers also offer calendar and or contacts sync services. Refer to our <a href="/providers/email">Email Provider recommendations</a> to choose an email provider and see if they also offer calendar and/or contacts sync.'
   website="/providers/email"
 %}