save image to Gallery
imageBytes can't null
return Map type
for example:{"isSuccess":true, "errorMessage":String?}
androidExistNotSave
On Android, if true, the save path already exists, it is not saved. Otherwise, it is saved
在安卓平台上,如果是true,则保存路径已存在就不在保存,否则保存
androidRelativePath
So for example androidRelativePath is Pictures/abc, so the save path is sdcard/Pictures/abc/${name}
例如androidRelativePath是 Pictures/abc,那么保存路径就是 sdcard/Pictures/abc/${name}