The tag is normalized immediately; malformed tags throw here. Matching and
catalog coverage are checked when an instance consumes the options, so the
same options object can be reused with different instances.
Parameters
locale: string
Returns Readonly<{locale:string}>
Throws
if the tag is not a well-formed IETF BCP 47 locale
Create per-call options for an explicit locale.
The tag is normalized immediately; malformed tags throw here. Matching and catalog coverage are checked when an instance consumes the options, so the same options object can be reused with different instances.