Use the document's charset to determine if/how to encode querystring

Whenever we resolve a URL, say from `anchor.href`, we should consider the
document's charset when encoding the querystring. This probably isn't the
most important feature, but it makes tens of thousands of WPT cases pass, e.g

/encoding/legacy-mb-tchinese/big5/big5-encode-href-errors-han.html?3001-4000 and
/encoding/legacy-mb-japanese/euc-jp/eucjp-encode-href-errors-han.html?17001-18000

DOM elements previous called `URL.resolveURL(...)`. They now call
`self.asNode().resolveURL(...)`, where `Node#resolveURL` will provide the
document's charset.

src/SemanticTree.zig

@@ -671,7 +671,7 @@ pub fn getNodeDetails(
 
         if (el.getAttributeSafe(comptime .wrap("href"))) |h| {
             const URL = lp.URL;
-            href = URL.resolve(arena, page.base(), h, .{ .encode = true }) catch h;
+            href = URL.resolve(arena, page.base(), h, .{ .encoding = page.charset }) catch h;
         }
 
         if (el.is(Element.Html.Input)) |input| {