Move help popup generation code
The first commit is just a small cleanup.
The idea behind this PR is to reduce a bit more the generated HTML files by moving the duplicated code into one place instead.
r? @kinnison
Unify escape usage
Fixes#63443.
I chose to keep the search text when pressing escape so when we focus on the search bar, we got the results again without needing to load them again. I also unified a bit a few things (maybe I should have done it in another commit, sorry...).
r? @Mark-Simulacrum
Improve searching in rustdoc and add tests
👋 I have made searching in rustdoc more intuitive, added a couple more tests and made a little shell script to aid testing. Closes#63005.
It took me quite a while to figure out how to run the tests for rustdoc (instead of running tests for other crates with rustdoc); the only pointer I found was [hidden in the rustc book](https://rust-lang.github.io/rustc-guide/rustdoc.html#cheat-sheet). Maybe this could be better documented? I shall be delighted to help if it is desirable.
Save crate filtering on rustdoc
Fixes#62929.
I added a hashmap and a hash encoding for the current crate list in case you have multiple crates handling on a same website (who talked about docs.rs?!). Like that, for each context, you have the filter crate selected.
r? @QuietMisdreavus
rustdoc: collapse blanket impls in the same way as normal impls
If the rustdoc setting _Auto-hide trait implementations documentation_ is activated (on by default), normal trait implementations are collapsed by default.
Blanket impls on the other hand are not collapsed. I'm not sure whether this is intended, but considering that the blanket impls for `From`, `Into`, `TryFrom`, ... are on every type, it would reduce the documentation bloat if these would also be collapsed when the setting is active.
(I'm not really familiar with the codebase and therefore just copied the code for the normal impl collapsing, but I could deduplicate it into a method, of course, too.)
Fix search results interactions
The bug is visible when you search for "none": the second tab is empty and therefore it messes with the classes. Then when you try to use arrows on the third tab, it just crashes (because only 2 "search-results" are present and you're on tab 3).
r? @QuietMisdreavus
Re-enable history api on file:// protocol
Fixes#57135.
I tested locally on chrome (since it was the browser having issues with history management on `file://` protocol) and it worked fine so I guess we can re-enable it.
r? @QuietMisdreavus
[rustdoc] Fix crates filtering box not being filled
Currently, the filter crate box (at the left of the search input) is always empty. To get the number of keys of dictionary in JS, you need to call `Object.keys()` on it.
r? @QuietMisdreavus
