Make Akita Web-Monetization-Provider-Neutral

[sharon-wang]

Although Coil is the only (known) Web Monetization Provider, I think it would be better for our wording in the extension to be provider-agnostic. Currently, for those not using a provider, they will see the following message in the extension:

You’ve spent X days on monetized sites, which is X% of your time online. In total, if you were using Coil you would have sent $X USD.

The Coil text is a link to the Coil website.

In place of Coil, we could change the wording to say "a provider", which is text-decorated so there's a hint to hover/click on "a provider". On hover/click, we can display a short blurb describing what a provider is and list some examples, such as Coil and any future providers.

The complication is that our calculation for estimated streamed payments (for those not using a provider) is currently based on the Coil rate, since Coil is the only provider option. When more providers show up, we'll have to provide a calculation per provider and give the user the ability to select which provider rate they want to go with.