__setDefaultTimeZone does not handle "Etc/UTC" timezone

[dlebedynskyi]

Which package?

@formatjs/intl-datetimeformat

Describe the bug

__setDefaultTimeZone can not handle timezone passed as "Etc/UTC" and throws "Invalid timeZoneName" errror.
Root case -

formatjs/packages/intl-datetimeformat/src/core.ts

Line 305 in 2a120fe

!IsValidTimeZoneName(timeZone, {

does not handle "Etc/UTC" code same way as

formatjs/packages/ecma402-abstract/CanonicalizeTimeZoneName.ts

Line 25 in 78d3558

if (ianaTimeZone === 'Etc/UTC' || ianaTimeZone === 'Etc/GMT') {

does.

Since IsValidTimeZoneName is called before CanonicalizeTimeZoneName can convert "Etc/UTC" to UTC, error is thrown.

To Reproduce

Issue is reproducible on Android devices in React Native App

• Setup your Android device to UTC +0 (for API 29-30 disable timezone from network, manually select UTC offset instead of region & city)
• call with TZ from device

 DateTimeFormat.__setDefaultTimeZone(tz)// "Etc/UTC"

Codesandbox URL

 DateTimeFormat.__setDefaultTimeZone("Etc/UTC") // will throw

Expected behavior

It is expected that UTC timezone would be selected, based on

formatjs/packages/ecma402-abstract/CanonicalizeTimeZoneName.ts

Line 25 in 78d3558

if (ianaTimeZone === 'Etc/UTC' || ianaTimeZone === 'Etc/GMT') {

.

Screenshots

N/A

Desktop (please complete the following information):

• OS: Android
• Version API 29, 30

Smartphone (please complete the following information):

• Device: any Android device
• OS: API 29, 30

Additional context

While IsValidTimeZoneName is by the spec - https://tc39.es/ecma402/#sec-isvalidtimezonename, it seems it does not account for "Etc/UTC" to "UTC" conversion, same way as

formatjs/packages/ecma402-abstract/CanonicalizeTimeZoneName.ts

Line 25 in 78d3558

if (ianaTimeZone === 'Etc/UTC' || ianaTimeZone === 'Etc/GMT') {

does.