Hide buttons generated by the `TryExamples` directive by default

[agriyakhetarpal]

Description

This PR hides the buttons from the TryExamples directive by default. This is helpful because the current method of ignoring particular pages based on their URL first loads the buttons and then hides them, which means that they are briefly displayed on that page in the documentation and then hidden – keeping them hidden and then selectively enabling them will minimise this latency and improve user experience.

Changes made

1. Made all try_examples_button buttons hidden at the time of generation by adding this keyword to the classList
2. Updated the loadTryExamplesConfig function in jupyterlite_sphinx.js to check for the try_examples_button hidden class instead and then remove hidden from the classList

Additional context

N/A

[agriyakhetarpal]

I have rebased this right now and opened a PR because I think it will be better for visibility, plus I would appreciate some help towards bringing this to completion. It's not fully working right now since the directives still seem to contain the try_examples_button hidden and therefore are not displayed, even when I try to remove the keyword from the classList. It has been a while since I worked on this, so I'm not sure what I was debugging back then.

[agriyakhetarpal]

I see why this is reasonable, but isn't that going to have the opposite effect on page where the button should be visible, where the page will load and then jump around as buttons are added ?

Thanks for the review, @Carreau. Yes, this will be a slight issue when someone reloads a page and if they are in the middle of a page when doing so – but at the top of the page, it should load as normal, because from there the buttons will be appended to the layout rather than being inserted into a position where the text moves because of the insertion. I am not sure if there is a cleaner way to do this.

[agriyakhetarpal]

I think this is partially working now – where it breaks is when a try_examples.json config file is not present, and therefore data.ignore_patterns will always be false. I'll try to move the logic for un-hiding the buttons into a separate function and then call it. This way, the currently hidden buttons can be un-hidden with or without the presence of the configuration file.

[agriyakhetarpal]

I think this is working now, marking it as ready for review. One small thing to figure out remains: the PR preview at https://jupyterlite-sphinx--173.org.readthedocs.build/en/173/directives/try_examples.html is not un-hiding the button with the custom blue-bottom CSS present in jupyterlite_sphinx.css. The button is visible in the stable documentation: https://jupyterlite-sphinx.readthedocs.io/en/stable/directives/try_examples.html

So this works for all sorts of buttons now (tested locally), except for these non-standard buttons that have user-defined CSS. Let me try to dig further, and meanwhile open this up for further comments.

[Carreau]

I will try to re-review.

I'm ok with this in principle. Still unsure if hiding or appending is the best, so I'd like someone else input on this anyway.