tools (common/utils): new methods to parse and generate file size with symbols:

- `parseSize` lets parse a size which can be either a int, or a string with a symbol like
  `Mio`
- `getSizeMultiplier` returns a tuple of size with it's multiplier symbol
- `getHumanSize` returns a string with size and adapted multiplier.

sat/plugins/plugin_misc_file.py

@@ -29,6 +29,7 @@ from sat.core import exceptions
 from sat.tools import xml_tools
 from sat.tools import stream
 from sat.tools import utils
+from sat.tools.common import utils as common_utils
 
 
 log = getLogger(__name__)
@@ -321,9 +322,7 @@ class FilePlugin:
         assert filename and not "/" in filename
         assert PROGRESS_ID_KEY in file_data
         # human readable size
-        file_data["size_human"] = "{:.6n} Mio".format(
-            float(file_data["size"]) / (1024 ** 2)
-        )
+        file_data["size_human"] = common_utils.getHumanSize(file_data["size"])
         d = xml_tools.deferDialog(
             self.host,
             _(CONFIRM).format(peer=peer_jid.full(), **file_data),