Store parser errors, source range filenames, source code filenames,
module source, and Rust parser errors as UTF-16 where they flow back
into JavaScript-visible strings. Keep byte-oriented source buffers
byte-backed.
Remove temporary PrimitiveString, ByteString, and UTF-8 detours from
JSON, RegExp, module debug logging, print formatting, and tests.
Produce JS-visible string results as UTF-16 at their source, including
numeric formatting, BigInt and BigFraction formatting, URI encoding,
console formatting, parser errors, regular expression errors, Intl and
Temporal records, LibUnicode locale boundaries, and LibWeb bindings.
Handle fractional radix formatting through the UTF-16 builder view.
This is a normative change in the ECMA-402 spec. See:
https://github.com/tc39/ecma402/commit/7508197
In our implementation, we don't have the affected AOs directly, as we
delegate to ICU. So instead, we must ensure we provide ICU a locale with
the relevant extension keys present.
