Add Attachment API (#3478)

* Add Attachment API
* repos/:owner/:repo/releases (add attachments)
* repos/:owner/:repo/releases/:id (add attachments)
* repos/:owner/:repo/releases/:id/attachments
* repos/:owner/:repo/releases/:id/attachments/:attachment_id

Signed-off-by: Jonas Franz <info@jonasfranz.de>

* Add unit tests for new attachment functions
Fix comments

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* fix lint

* Update vendor.json

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* remove version of sdk

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Fix unit tests
Add missing license header

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add CreateReleaseAttachment
Add EditReleaseAttachment
Add DeleteReleaseAttachment

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add filename query parameter for choosing another name for an attachment

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Fix order of imports

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Restricting updatable attachment columns

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* gofmt

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Update go-sdk
Replace Attachments with Assets

Signed-off-by: Jonas Franz <info@jonasfranz.de>

* Update go-sdk

Signed-off-by: Jonas Franz <info@jonasfranz.de>

* Updating go-sdk and regenerating swagger

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add missing file of go-sdk

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Change origin of code.gitea.io/sdk to code.gitea.io/sdk
Update code.gitea.io/sdk

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Update swagger

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Update updateAttachment

package.json

@@ -4,4 +4,4 @@
         "less": "^2.7.2",
         "less-plugin-clean-css": "^1.5.1"
     }
-}
+}