Add new storage backend: Dropbox (#103) (#251)

* Add new storage backend: Dropbox (#103)

* Remove duplicate check

* Add concurrency level for parallel upload to dropbox.

* Fixed some instabilites. Changed default concurrency to 6.

* Added some env config vars to readme. WIP

* Wrap errors for storage backend creation.

* Fixed token issue, added OAuth2 including recipe and docs.

* Readme typo fix

* Test for dropbox integration

* Update info and TOC

* Missed a file

* Docker-compose fix

* Fix endpoint connection

* Fix container names

* Fix log fetching

* Fix log fetching (again)

* Print command output to logs

* Addressing comments part 1

* Address comments part 2

* OpenAPI Mock spec path adjusted
* Dropbox FileMetadata reflection refactored
* NaturalNumber type added

* Add OAuth2 mock server for CI testing

* Fix env name of oauth2 endpoint

* Remove hostname

* Add forgotten change to commit...

* Fix oauth2 endpoint

"Worked on my machine"

* Try again

* Try suggested hostname again

* Fix docker internal DNS resolving issues (as suggested by oauth2 mock docs)

* Add docker network, remove hostname

* Network not external

* Last hostname try

* Add more delay, add oauth2 endpoint log

* Temp CI log output of command even when failing

* Try different config and method

* Add custom server-hostname. Rename test folder to accellerate debugging

* Try that fix again

* Adding quotes

* Port fix attempt

* Try localhost

* Try extra hosts

* Change network mode

* Undo some changes

* Use static IP

* Remove specific IP binding

* Change to default net driver

* Fix static IP

* Squash for revert

* Revert "Squash for revert"

This reverts commit e9b617be9a.

* Actual fix for CI testing from #257

go.mod

@@ -20,6 +20,13 @@ require (
 	golang.org/x/sync v0.3.0
 )
 
+require (
+	github.com/golang/protobuf v1.5.2 // indirect
+	golang.org/x/oauth2 v0.0.0-20221014153046-6fdb5e3db783 // indirect
+	google.golang.org/appengine v1.6.7 // indirect
+	google.golang.org/protobuf v1.28.1 // indirect
+)
+
 require (
 	github.com/Azure/azure-sdk-for-go/sdk/azcore v1.6.0 // indirect
 	github.com/Azure/azure-sdk-for-go/sdk/internal v1.3.0 // indirect
@@ -28,6 +35,7 @@ require (
 	github.com/docker/distribution v2.8.2+incompatible // indirect
 	github.com/docker/go-connections v0.4.0 // indirect
 	github.com/docker/go-units v0.4.0 // indirect
+	github.com/dropbox/dropbox-sdk-go-unofficial/v6 v6.0.5
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/fatih/color v1.13.0 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect