Assume unitless numbers are in default unit

Bug in `MemoryParamType.convert` was failing if a unit was not given
with a value. Similar to `DurationParamType` it assumes that numbers
without a unit are given in the default unit of the type.

flepimop/gempyor_pkg/src/gempyor/shared_cli.py

@@ -318,7 +318,7 @@ def convert(
         if (m := self._regex.match(value)) is None:
             self.fail(f"{value!r} is not a valid memory size.", param, ctx)
         number, _, _, unit = m.groups()
-        unit = unit.lower()
+        unit = self._unit if unit is None else unit.lower()
         if unit == self._unit:
             result = float(number)
         else:

flepimop/gempyor_pkg/tests/shared_cli/test_memory_param_type_class.py

@@ -57,6 +57,10 @@ def test_convert_acts_as_identity(unit: str, as_int: bool, number: int | float)
         ("kb", True, "2tb", 2147483648),
         ("mb", False, "0.1gb", 0.1 * 1024.0),
         ("mb", True, "0.1gb", 103),
+        ("gb", False, "4", 4.0),
+        ("gb", True, "4", 4),
+        ("mb", False, "1234.56", 1234.56),
+        ("mb", True, "1234.56", 1235),
     ),
 )
 def test_exact_results_for_select_inputs(