fix(parser): avoid panic on escaped string export names (#26146)

## Summary

Fix a parser panic when a string-named export decodes to a literal `\u` sequence.

Lone-surrogate validation now uses the metadata captured by the lexer instead of rescanning decoded string contents. This also prevents false diagnostics for names such as `"\\uD800"`.

## Before:

```

thread 'main' (10990283) panicked at crates/oxc_ast/src/ast_impl/literal.rs:89:42:
end byte index 4 is out of bounds for string of length 0
stack backtrace:
   0: __rustc::rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::str::slice_error_fail_rt
   3: core::str::slice_error_fail
   4: <core::ops::range::RangeTo<usize> as core::slice::index::SliceIndex<str>>::index
   5: <str as core::ops::index::Index<core::ops::range::RangeTo<usize>>>::index
   6: <oxc_ast::ast::literal::StringLiteral>::is_string_well_formed_unicode
   7: <oxc_parser::ParserImpl<oxc_parser::config::NoTokensParserConfig>>::parse_module_export_name
```