Change the created archive name in CompressJob

If a single item in zipped, the filename extension of this file is
replaced by ".zip" to determine the created archive name.

If several items are zipped together, the created archive name is
"Archive.zip".

Bug: 442295418
Flag: com.android.documentsui.flags.zip_ng_ro
Test: atest DocumentsUIGoogleTests:com.android.documentsui.services.CompressJobTest
Change-Id: I2b731f108bc485ca5389971b595d2b1619734a87