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.
On Windows, ICU does not look at the TZ environment variable at all. So
to support changing time zones in test-js, let's set ICU's default time
zone directly.
Note that we no longer deal with "null" time zone strings. We just cache
whatever ICU thinks is the current time zone before attempting to change
it, for which we never have a null result.
Co-authored-by: Andrew Kaster <andrew@ladybird.org>
