Operations specific to DateTimeFormat should have names indicating that

[gibson042]

(originally posted by @gibson042 in #923 (comment))

e.g., {Basic,BestFit}Matcher → DateTimeFormat{Basic,BestFit}Matcher

[anba]

Maybe keep "FormatMatcher" together to match the constructor option "formatMatcher"? That means: {Basic,BestFit}DateTimeFormatMatcher.

Intl.DateTimeFormat is currently the only Intl constructor which accepts a "formatMatcher" option, so there's no latent ambiguity about the name.