`declare const` should be used instead of `const` in `d.ts` files

[auvred]

node-unicode-data/scripts/utils.js

Line 156 in 9d1e61d

? `const data: string[];\nexport default data;`

and many similar with "skipLibCheck": false produce this error

$ npm exec tsc -- --noEmit

node_modules/@unicode/unicode-16.0.0/Bidi_Mirroring_Glyph/index.d.ts:1:1 - error TS1046: Top-level declarations in .d.ts files must start with either a 'declare' or 'export' modifier.

1 const data: Map<number, string>;
  ~~~~~


Found 1 error in node_modules/@unicode/unicode-16.0.0/Bidi_Mirroring_Glyph/index.d.ts:1