Improve document extraction and including a document extraction command (#17183)

* Add extract documents content command

* Adding the extraction command and making the pure go pdf library as secondary option

* Improving the memory usage and docextractor interface

* Enable content extraction by default in all the instances

* Tiny improvement on archive indexing

* Adding App interface generation and the opentracing layer

* Fixing linter errors

* Addressing PR review comments

* Addressing PR review comments

model/config.go

@@ -1430,7 +1430,7 @@ func (s *FileSettings) SetDefaults(isUpdate bool) {
 	}
 
 	if s.ExtractContent == nil {
-		s.ExtractContent = NewBool(false)
+		s.ExtractContent = NewBool(true)
 	}
 
 	if s.ArchiveRecursion == nil {