Rollup merge of #81275 - jyn514:time-render, r=wesleywiser

Fix <unknown> queries and add more timing info to render_html

Closes https://github.com/rust-lang/rust/issues/81251.

##  Fix `<unknown>` queries

This happened because `alloc_query_strings` was never called.

##  Add more timing info to render_html

This still has some issues I'm not sure how to work out:

- `create_renderer` and `renderer_after_krate` aren't shown by default.
  I want something like `verbose_generic_activity_with_arg`, but it doesn't exist.

I'm also not sure how to show activities that aren't on by default - I
tried `-Z self-profile -Z self-profile-args=all`, but it didn't show up.

r? `@wesleywiser`

src/librustdoc/html/render/mod.rs

@@ -383,6 +383,10 @@ crate fn initial_ids() -> Vec<String> {
 
 /// Generates the documentation for `crate` into the directory `dst`
 impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
+    fn descr() -> &'static str {
+        "html"
+    }
+
     fn init(
         mut krate: clean::Crate,
         options: RenderOptions,