Have all operators exit gracefully when no input is provided

[randomorder]

Would be good to handle this condition gracefully in all operators.Investigation on current situation is required to figure out which ones need to be fixed.

• [x] ZipInspector

• [x] RSYNCOperator

• [x] MoveFilesOperator

• [x] GDALWarpOperator

• [x] GDALAddoOperator

• [x] GDALTranslateOperator

• [x] GDALInfoOperator

• [x] S1MetadataOperator

• [x] Landsat8MTLReaderOperator

• [x] Landsat8ThumbnailOperator

• [x] Landsat8ProductDescriptionOperator

• [x] Landsat8GranuleJsonFileOperator

• [x] Landsat8SearchOperator

• [x] Landsat8DownloadOperator

• [x] Landsat8ProductZipFileOperator

• [x] Sentinel2ThumbnailOperator

• [x] Sentinel2MetadataOperator

• [x] Sentinel2ProductZipOperator

[randomorder]

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