fix: sync sourceCodeLocation.attrs keys with adjusted SVG/MathML/XML attribute names

[TrevorBurnham]

Closes #318

Summary

When parsing foreign content (SVG, MathML), parse5 adjusts attribute names from their tokenizer-lowercased form to spec-correct casing (e.g. viewbox → viewBox). However, the keys in sourceCodeLocation.attrs were not updated to match, so element.attrs would have viewBox while sourceCodeLocation.attrs only had viewbox.

Changes

• packages/parse5/lib/common/foreign-content.ts — Updated adjustTokenSVGAttrs, adjustTokenMathMLAttrs, and adjustTokenXMLAttrs to also rename the corresponding key in token.location.attrs when adjusting an attribute name.
• packages/parse5/lib/parser/parser-location-info.test.ts — Added a regression test parsing <svg viewBox="0 0 100 100"> and asserting that location.attrs uses the camelCase key viewBox, not viewbox.

Before

const fragment = parseFragment('<svg viewBox="0 0 100 100"></svg>', {
  sourceCodeLocationInfo: true,
});
const svg = fragment.childNodes[0];

svg.attrs[0].name;                         // 'viewBox' ✓
Object.keys(svg.sourceCodeLocation.attrs); // ['viewbox'] ✗ — mismatch

After

svg.attrs[0].name;                         // 'viewBox' ✓
Object.keys(svg.sourceCodeLocation.attrs); // ['viewBox'] ✓ — matches