By leveraging import maps we can get rid of *most* of the remaining `require`-calls in the `src/display/`-folder, since we should strive to use modern `import`-statements wherever possible.
The only remaining cases are Node.js-specific dependencies, since those seem very difficult to convert unless we start producing a bundle *specifically* for Node.js environments.
Until now we've not actually had *any* tests that ensure that the *official* PDF.js API exposes the intended functionality, which means that things can easily break accidentally.
