Add approximatelySign to NumberFormatPartTypeRegistry for ES2023

[Copilot]

The NumberFormatPartTypeRegistry interface was missing the approximatelySign part type, which is used by Intl.NumberFormat.formatRangeToParts() when ranges round to approximately the same value.

This caused TypeScript compilation errors when filtering format parts:

const nf = new Intl.NumberFormat("en-US", {
  style: "currency",
  currency: "EUR",
  maximumFractionDigits: 0,
});

// This would fail with TS error before the fix
nf
  .formatRangeToParts(value.from, value.to)
  .filter((part) => part.type !== "approximatelySign")
  .map((part) => part.value)
  .join("");

Changes:

• Added approximatelySign: never; to NumberFormatPartTypeRegistry interface in src/lib/es2023.intl.d.ts
• Updated ES2023 intl test to include validation of the new part type
• Updated test baselines to reflect the change

The change follows the existing pattern used across ES versions for extending the NumberFormatPartTypeRegistry with new part types, ensuring TypeScript properly recognizes approximatelySign as a valid format part type.

Fixes #61960.

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[Renegade334]

approximatelySign is a range-only type – in an ideal world, a separate NumberFormatRangePartTypeRegistry extends NumberFormatPartTypeRegistry interface would be the proper place for this.