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

services/docextractor/interface.go

@@ -10,5 +10,5 @@ import (
 // Extractors define the interface needed to extract file content
 type Extractor interface {
 	Match(filename string) bool
-	Extract(filename string, file io.Reader) (string, error)
+	Extract(filename string, file io.ReadSeeker) (string, error)
 }