Print input and output file sizes

[marcospb19]

Examples:

$ ouch compress input output.gz

-[INFO] Successfully compressed 'output.gz'
+[INFO] Input file size:   6.11 kiB
+[INFO] Output file size:   2.55 kiB
+[INFO] Successfully compressed to 'output.gz'

And

$ ouch decompress output.zst

-[INFO] Successfully decompressed archive in current directory
-[INFO] Files unpacked: 1
+[INFO] File "/home/marcospb19/ouch/output.gz" decompressed to "./output"
+[INFO] Input file size:   2.55 kiB
+[INFO] Output file size:   6.11 kiB