Better mobile device detection for interactive examples buttons

[agriyakhetarpal]

Description

This PR closes #140; it moves the logic from the CSS styles for disabling the interactive buttons and uses a better heuristic via our JavaScript code; i.e., the navigator.userAgent's value to check what sort of device a user is on. As a fallback, the screen size check has also been kept. A resize handler with 250ms debouncing has also been added here to check the screen size if the buttons haven't been disabled already.

I have to note that this also disables them on devices like iPads and other tablets, which can be reconsidered if someone raises this point. The CSS has been removed, as #141 (comment) is not applicable due to the use of user agents to detect the platform.

cc: @gabalafou

[agriyakhetarpal]

I rebased and updated the changes to work with the caching of the try_examples.json file, so that the mobile device detection is also cached and the checks for the page's resize comply. Thanks for the review, @Carreau!