MM-60115, MM-62436, MM-62493: Compliance export downloads from local and s3; e2e tests (#29806)

* add ZipReader method to filestore and file/s3 backends

to merge

to merge

* add WriteStreamResponse as an alternative to WriteFileResponse

* add generated layers

* enable download link; download job endpoint now streams export dir zips

* fix MM-62493

* re-enable e2e tests--we have download links, folks

* Add tests for ZipReader in filestore and s3store

* remove unnecessary error return on ZipReader

* little cleanup

* improve tests; some refactoring: s.Nil(err) -> s.NoError(err)

* blank commit

* backwards compatability for pre-10.5 job downloads

* compress file response; better errors; better comments; PR comments

* update generated app layers

* improve/widen tests; improve comments; simplify localstore ZipReader

* regenerate layers

* follow GoDoc conventions

* update generated layers

* remove unnecessary comment

* in jobs/job-id/download, clean exportDir before sending to ZipReader

* better comments; add an error return on ZipReader

* improve file permissions

* adjust tests for new error returns

* linting

* i18n

server/platform/shared/filestore/filesstore.go

@@ -40,6 +40,7 @@ type FileBackend interface {
 	ListDirectory(path string) ([]string, error)
 	ListDirectoryRecursively(path string) ([]string, error)
 	RemoveDirectory(path string) error
+	ZipReader(path string, deflate bool) (io.ReadCloser, error)
 }
 
 type FileBackendWithLinkGenerator interface {