Prevent start panic due to missing DotEscape function

Unfortunately #19169 causing a panic at startup in prod mode. This was hidden by dev
mode because the templates are compiled dynamically there. The issue is that DotEscape
is not in the original FuncMap at the time of compilation which causes a panic.

Ref #19169

Signed-off-by: Andrew Thornton <art27@cantab.net>

modules/templates/helper.go

@@ -379,6 +379,7 @@ func NewFuncMap() []template.FuncMap {
 		},
 		"Join":        strings.Join,
 		"QueryEscape": url.QueryEscape,
+		"DotEscape":   DotEscape,
 	}}
 }