docs: Add version information to application and function XML elements

* Do a git blame on the embedded XML application or function element.

* From the commit hash, grab the summary line.

* Do a git log --grep <summary> to find the cherry-pick commits in all
  branches that match.

* Do a git patch-id to ensure the commits are all related and didn't get
  a false match on the summary.

* Do a git tag --contains <commit> to find the tags that contain each
  commit.

* Weed out all tags not ..0.

* Sort and discard any .0.0 and following tags where the commit
  appeared in an earlier branch.

* The result is a single tag for each branch where the application or function
  was defined.

The applications and functions defined in the following files were done by
hand because the XML was extracted from the C source file relatively recently.
* channels/pjsip/dialplan_functions_doc.xml
* main/logger_doc.xml
* main/manager_doc.xml
* res/res_geolocation/geoloc_doc.xml
* res/res_stir_shaken/stir_shaken_doc.xml

main/logger_doc.xml

@@ -3,6 +3,7 @@
 <?xml-stylesheet type="text/xsl" href="appdocsxml.xslt"?>
 <docs xmlns:xi="http://www.w3.org/2001/XInclude">
 	<function name="LOG_GROUP" language="en_US">
+		<since><version>18.21.0</version><version>20.6.0</version><version>21.1.0</version></since>
 		<synopsis>
 			Set the channel group name for log filtering on this channel
 		</synopsis>