Which @angular/* package(s) are relevant/related to the feature request?

localize

Description

I would like to use custom IDs on ICU expression translations.

The following template

<h1 i18n="@@IcuPluralTest">ICU plural test {test, plural, =0 {now} other {{{test}} minutes}}</h1>

Results in two translations in json output format:

"IcuPluralTest": "ICU plural test {$ICU}",
"5042638883563958958": "{VAR_PLURAL, plural, =0 {now} other {{INTERPOLATION} minutes}}",

However, I have no way to assign a custom ID to the nested ICU expression

Proposed solution

Enable a syntax like

<h1 i18n="@@IcuPluralTest">ICU plural test {:@@IcuPluralTestNested:test, plural, =0 {now} other {{{test}} minutes}}</h1>

that allows assigning an ID to the nested ICU expression

Alternatives considered

As a workaround, a simple interpolation can be used in the template

<h1 i18n="@@IcuPluralTest">ICU plural test {{testPlural}}</h1>

with the ICU expression being defined in the .ts file using intl-messageformat

testPlural = new IntlMessageFormat($localize`:@@IcuPluralTestNested:{test, plural, =0 {now} other {# minutes}}`, $localize.locale).format(this as any);