Data provider: match on TinyStr instead of &str

[sffc]

We can be more efficient by matching on TinyStr by integer value rather than &str.

Blocked on zbraniecki/tinystr#17

CC @zbraniecki

[zbraniecki]

Unblocked! :) https://crates.io/crates/tinystr

[sffc]

I got the following to work on nightly:

        const CARDINAL: TinyStr16 = tinystr16!("cardinal");
        const ORDINAL: TinyStr16 = tinystr16!("ordinal");
        match data_key.sub_category {
            CARDINAL => self.cardinal_rules.as_ref(),
            ORDINAL => self.ordinal_rules.as_ref(),
            _ => return Err(data_key.into()),
        }

It doesn't work on stable. If I try, it says:

error[E0658]: procedural macros cannot be expanded to expressions
  --> components/cldr-json-data-provider/src/transform/plurals.rs:80:36
   |
80 |         const ORDINAL: TinyStr16 = tinystr16!("ordinal");
   |                                    ^^^^^^^^^^^^^^^^^^^^^
   |
   = note: see issue #54727 <https://github.com/rust-lang/rust/issues/54727> for more information

error: aborting due to 3 previous errors

[sffc]

Also see zbraniecki/tinystr#22

[sffc]

The code from #212 (comment) works now in rustc 1.46.0 (04488afe3 2020-08-24).