gee12

Results 3 issues of gee12

Add russian translate; Move string constants to string.xml; Increment SDK version to 28

Added search and sorting in categories list and images list

Removed passing the `mimeType` to `makeFile()` for files when copying with `DocumentFile.copyFolderTo()`, which is why the extension of the copied files changed (because in system file`MimeTypeMap.java` by this `mimeType` has...