List Backgrounds (#568)

Return the updated list when setting a list background

Add swagger docs for unsplash methods

Add unsplash info to search results

Fix misspell

Fix lint

Add rights check for setting and getting backgrounds

Show unsplash information when loading a single list

Make application id for pingbacks configurable

Remove old backgrounds when setting a new one

Return 404 if the list does not have a background

Implement getting list backgrounds

Implement actually setting a photo from unsplash as list background

go mod tidy

Add migration for background file id

Roughly implement setting a list background from unsplash

Implement saving a background

Add migration for unsplash photo table

Add unsplash search

Fix parsing page param

Fix parsing page param

Fix background config

Add unsplash wrapper library

Add enabled background providers to info endpoint

Add config options for backgrounds

Add unsplash background provider

Add routing handler for backgrounds

Add basic background provider interface

Co-authored-by: kolaente <k@knt.li>
Reviewed-on: https://kolaente.dev/vikunja/api/pulls/568

pkg/files/error.go

@@ -50,3 +50,20 @@ func IsErrFileIsTooLarge(err error) bool {
 	_, ok := err.(ErrFileIsTooLarge)
 	return ok
 }
+
+// ErrFileIsNotUnsplashFile defines an error where a file is not downloaded from unsplash.
+// Used in cases whenever unsplash information about a file is requested, but the file was not downloaded from unsplash.
+type ErrFileIsNotUnsplashFile struct {
+	FileID int64
+}
+
+// Error is the error implementation of ErrFileIsNotUnsplashFile
+func (err ErrFileIsNotUnsplashFile) Error() string {
+	return fmt.Sprintf("file was not downloaded from unsplash [FileID: %d]", err.FileID)
+}
+
+//IsErrFileIsNotUnsplashFile checks if an error is ErrFileIsNotUnsplashFile
+func IsErrFileIsNotUnsplashFile(err error) bool {
+	_, ok := err.(ErrFileIsNotUnsplashFile)
+	return ok
+}