[Bug] i.sentinel.download: give warning instead of errors if single files are corrupt

[ninsbl]

i.sentinel.download

Describe the bug
Downloading does not succeed if there are cruft files on either the data provider side or in the directory to download to (".incomplete" files). i.sentinel.download should catch these cases and give a warning instead of an error...

To Reproduce
Not straight forward to reproduce. Put a protected S1A_IW_GRDH_1SDV_20230930T043121_20230930T043156_050552_0616C8_936A.SAFE.zip.incomplete file into the directory to download to or try to download S3B_OL_1_EFR____20230913T085813_20230913T090113_20230913T203837_0180_084_050_1800_PS2_O_NT_003.zip from the Norwegian Ground Segment...

Expected behavior
i.sentinel.download should throw a warning istead of erroring out, esp. in the case of ".incomplete" files all downloads are blocked.

System description (please complete the following information):

• Operating System: Ubuntu Linux
• GRASS GIS version 8.4

Additional context
Happens on CIFS mounted storage that incomplete files get stuck and are hard to remove. Issues on the provider side may be specific to the Norwegian Ground Segment....