test: adding test cases for real unicode variants
test: adding test cases for real unicode variants

CLDR has a list of valid variants: https://github.com/unicode-org/cldr/blob/latest/common/validity/variant.xml (IANA maintains a list of valid locales: https://www.iana.org/assignments/language-subtag-registry/language-subtag-registry )

projectfluent/fluent.js,projectfluent/fluent.js,zbraniecki/fluent.js,zbraniecki/fluent.js,projectfluent/fluent.js