Sloeber does not check the filesize nor checksum of the downloaded files

[jantje]

The arduino framework provides checksums and filesize information to make the download process a bit safer.
However sloeber does not check these.
As Sloeber puts the downloaded file in the downloads folder and never tries to re download this means that once a corrupted/incomplete file has been downloaded the user needs to manually delete the file form the downloads folder.
This may look like a simple workaround but that is not the case as there are many files in this folder and it is hard to identify the culprit file(s).
Moreover I noticed more and more download fails (both locally and during the github build).
So this long overdue functionality finally gets some attentions.

[jantje]

It seems Arduino IDE is not testing the size and as a consequence some sizes are wrong so Sloeber can not test the size as well
https://github.com/arduino/arduino-cli/blob/4d24bf8809d5c4e24412da32d1e444634f791029/internal/arduino/resources/checksums.go#L95