CI: Check help tags for errors (duplicates, missing, etc) (#13865)

- Run the doc make html awk script, which also checks, that all
  referenced help tags exists.
- Run the doc maketags awk script, which checks for duplicates
- in case of any error in the previous two steps, exit the CI with
  an error and show the errors.log file, that is generated by the
  previous 2 steps

Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/doc/maketags.awk

@@ -21,6 +21,13 @@ NR == 1 { nf=split(FILENAME,f,".")
 	gsub(/%/,"\\%");
 
 	nf=split($0,tag,"	");
+	if (counttag[tag[1]] > 0)
+	{
+		print "==============" > "errors.log"
+		print "Duplicate Tag " tag[1] > "errors.log"
+		print "==============" > "errors.log"
+	}
+	counttag[tag[1]]++
 	tagkey[t]=tag[1];tagref[t]=tag[2];tagnum[t]=NR;
 	print $1 "	" $2 "	line " NR >"tags.ref"
 	n=split($2,w,".");