[Plugin] April Fools Languages joke

[seshrs]

Context

I've been meaning to include something like this in Primer Spec for years now 😅 (It started with a small "Project 6" prank on eecs485.org, and then expanded to a Halloween-themed prank on eecs485.org.)

In #157, I introduced a limited-edition spooky theme that will only appear around Halloween. My design goals:

• The pranks/jokes that are not vital for loading the page should be lazy-loaded and executed asynchronously. (They should not impact the page load experience.)
• Students need to opt-in for the pranks/jokes to take effect. Even after opting in, there should be a clear and easy way to opt out.

This PR introduces an April Fools gag using the same design goals. This PR also introduces a way for website admins to opt-out of showing these jokes if they really don't want them 😛

April Fools Languages

This PR adds a "Language selector" popover to all Primer Spec pages around April Fools, from March 29 until April 3.

The language popover appears next to the settings icon:

Clicking the toggle button opens a popover with a language-dropdown. We assume that the page's language is in English:

The language-dropdown provides three other options: Pig Latin, Pirate, and Upside Down:

Here's what the page looks like after selecting "Upside Down":

Notice how the language-selection only affects the main content. Website viewers can easily revert the changes either by clicking "English" in the language-selector or by refreshing the page. (The "language" setting isn't persisted.)

Validation

PR Preview website: https://preview.sesh.rs/previews/eecs485staff/primer-spec/197/

Visit any page in the PR preview website above, then add ?enable_april_fools_languages=1 to the end of the URL. For example:

• https://preview.sesh.rs/previews/eecs485staff/primer-spec/197/?enable_april_fools_languages=1
• https://preview.sesh.rs/previews/eecs485staff/primer-spec/197/demo/diagrams.html?enable_april_fools_languages=1

Future plans

I would ideally like to introduce three more April Fools jokes with different premises. Then, we could cycle between the jokes each year — students in 4-year university programs would get to see a different joke each year!

[github-actions]

The spec from this PR is available at https://preview.sesh.rs/previews/eecs485staff/primer-spec/197/.

^{(Available until Mon Aug 15 2022.)}

[seshrs]

@noah-weingarden if you are interested and have bandwidth, I'd appreciate if you could check out this PR! Feel free to comment with other ideas and suggestions too :)