Keep Dapp detection but only for greaselion sites

[bbondy]

We thought of removing Dapp detection completely, but I think it's still useful. It has some false positives currently where we show the infobar which is not good.

We could instead use Greaselion to show the Crypto Wallets infobar for a whitelist of sites.
It'd be ok if we don't show it for sites, it's just an onboarding mechanism though that we can use for popular Dapps to help users that would want to use those Dapps.

See this for relevant code sections:

yeah, greaselion side looks like this: https://github.com/brave/brave-site-specific-scripts/blob/master/scripts/brave_rewards/publisher/youtube/publisherInfo.ts#L204-L226

brave extension handler is here: https://github.com/brave/brave-core/blob/502215e0dbbbe0f1a09de9325f95c18b84eeec5c/components/brave_extension/extension/brave_extension/background/greaselion.ts#L327-L421

This will supersede this work:
brave/brave-core#7321

As part of this work, we'll have to get rid of the lazy loading.

[bbondy]

superseded by #18213