Regressions from 3.16

[Awlexus]

Hi, we ran into a couple of issues updating this library from 3.16.4 to 3.17

1. Cldr.Unit.parse_unit_name returns string instead of atom

iex> Cldr.Unit.parse_unit_name("mg/dl")
# Before 3.17
{:ok, :milligram_ofglucose_per_deciliter}
# After 3.17
{:ok, "milligram_ofglucose_per_deciliter"}

2. Cannot format Unit with unit_name "mg/dl"

The following function call does not work in 3.17 any more

iex> Cldr.Unit.to_string!(Cldr.Unit.new!("milligram_ofglucose_per_deciliter", "120.5"), style: :short)
# Before 3.17
"120.5 mg/dL"
# After 3.17
** (Cldr.Unit.NoPatternError) No format pattern was found for unit Cldr.Unit.new!("milligram_ofglucose_per_deciliter", "120.5") with grammatical case :nominative, gender :neuter and plural type :other
     stacktrace:
       (ex_cldr_units 3.17.0) lib/cldr/unit/format.ex:807: Cldr.Unit.Format.get_unit_pattern!/3
       (ex_cldr_units 3.17.0) lib/cldr/unit/format.ex:714: Cldr.Unit.Format.do_iolist/3
       (ex_cldr_units 3.17.0) lib/cldr/unit/format.ex:682: Cldr.Unit.Format.do_iolist/3
       (ex_cldr_units 3.17.0) lib/cldr/unit/format.ex:631: Cldr.Unit.Format.to_iolist/4
       (ex_cldr_units 3.17.0) lib/cldr/unit/format.ex:639: Cldr.Unit.Format.to_iolist/4
       (ex_cldr_units 3.17.0) lib/cldr/unit/format.ex:470: Cldr.Unit.Format.to_iolist/3
       (ex_cldr_units 3.17.0) lib/cldr/unit/format.ex:201: Cldr.Unit.Format.to_string/3
       (ex_cldr_units 3.17.0) lib/cldr/unit/format.ex:316: Cldr.Unit.Format.to_string!/3