feat: add donation request

[benfurber]

After a (logged in) user clicks/taps to download files on a how-to, etc. a modal should be added to invite the user to make a donation.

Must haves:

• Generic DonationRequest component in the component library. Responsive. Flexbox.
• Update Modal to accomidate components that need to be responsive
• Add listener for when iframe changes on donation accepted
• Put behind beta-tester wrapper and only for how-tos
• Test flow on cypress
• Wrap around the DownloadFileFromLink component
• Wrap around the DownloadStaticFile component
• All the text controlled by app common component

Should have:

• Common component in the app for the iframe/config option
• Some config by platform for the iframe
• Add labels convention to component library

[benfurber]

I've been thinking about the user flow for when user actually do make a donation.

There are some url redirect options, though probably not what we want.

Users will/should expect a thank you/completion page. So I'm thinking about setting up a event listener that waits for the thank you page to be visible and when it is, changes the wording of the skip button to 'download now' or similar.

[benfurber]

I'm been doing some playing around to try and get the embed to be 'perfect' across all viewpoint sizes. I haven't got there yet but I've spent enough time on it(!) There might be some more options from donor box to try later down the line.