Rollup merge of #84150 - jsha:defer-search-js, r=GuillaumeGomez

rustdoc: move some search code into search.js

This reduces main.s from 3094 lines to 1587. Also it saves some bytes
of download in the case where search isn't used.

There were a fair number of variables that needed to be accessible in
both main.js and search.js, but I didn't want to put too many symbols in
the global namespace, so I consolidated much of the search-related
state and functions into a new object `window.searchState`.

Demo at https://hoffman-andrews.com/rust/move-search/std/?search=foo

Author: Dylan-DPC

src/librustdoc/html/layout.rs

@@ -113,7 +113,8 @@ crate fn render<T: Print, S: Print>(
     <section class=\"footer\"></section>\
     {after_content}\
     <div id=\"rustdoc-vars\" data-root-path=\"{root_path}\" data-current-crate=\"{krate}\" \
-       data-search-js=\"{root_path}search-index{suffix}.js\"></div>
+       data-search-index-js=\"{root_path}search-index{suffix}.js\" \
+       data-search-js=\"{static_root_path}search{suffix}.js\"></div>
     <script src=\"{static_root_path}main{suffix}.js\"></script>\
     {extra_scripts}\
 </body>\

src/librustdoc/html/render/write_shared.rs

@@ -222,6 +222,7 @@ pub(super) fn write_shared(
             &format!(" = {}", serde_json::to_string(&themes).unwrap()),
         ),
     )?;
+    write_minify("search.js", static_files::SEARCH_JS)?;
     write_minify("settings.js", static_files::SETTINGS_JS)?;
     if cx.shared.include_sources {
         write_minify("source-script.js", static_files::sidebar::SOURCE_SCRIPT)?;
@@ -409,7 +410,7 @@ pub(super) fn write_shared(
     write_crate("search-index.js", &|| {
         let mut v = String::from("var searchIndex = JSON.parse('{\\\n");
         v.push_str(&all_indexes.join(",\\\n"));
-        v.push_str("\\\n}');\ninitSearch(searchIndex);");
+        v.push_str("\\\n}');\nif (window.initSearch) {window.initSearch(searchIndex)};");
         Ok(v.into_bytes())
     })?;