Fix extensions to work with Smarty3 - backticks

In order to replace Smarty 2 with Smarty 3 we need to make minor changes to extensions so that they are compatible

UPDATE - the backticks seem to be less hurty than I thought so I misunderstood @larssg anaysis of when they DO cause issues

Ref https://github.com/kanshin/CakeSmarty/blob/master/vendors/Smarty-3.0.9/SMARTY2_BC_NOTES

• Backticks should no longer be used in strings - unfortunately the advertised way of doing crmUrl included backticks - we should add to civix upgrade to include doing a regex to fix these

href="{crmURL p='civicrm/participant/add' q="reset=1&action=add&context=standalone&eid=$event.id"}"

this regex seems to work to find them ".*\$.*"

• Find extensions with older civix & run regex on them - for those with backticks this will fix. For the others it will allow Smarty3 to be run in the transition period
• Patch / hack Smarty2 to give deprecation notices for the above
• When we are closer to transitioning consider temporarily hacking string replace into smarty 3 fetch function

Extension list

• CiviRules
• UK Gift Aid extensions/ukgiftaid!41 (merged)
• CiviCalender https://github.com/agiliway/com.agiliway.civicalendar/pull/34
• Elections extensions/elections!4