Support overrides to the eTLD+1 exception policy from default adblock filter lists

[antonok-edm]

The default adblock engine, into which the default Brave filter lists are loaded, is subject to first-party exceptions to improve web compatibility when in standard Shields blocking mode, as per https://brave.com/privacy-updates/9-web-compat-blocking/.

However, there are cases where we can verify that some first-party resources are an invasion of privacy, cause excessive CPU load, or are otherwise harmful to users and do not break pages - in this case we'd like a way to override the first-party exception policy, and ensure that those requests are blocked anyways in standard Shields mode.

This can be accomplished by loading some filters into a separate adblock engine without the first-party exceptions.

[antonok-edm]

Now that the adblock engines are merged (#5461), this should be significantly easier to implement. We can create a new component in https://github.com/brave/brave-core-crx-packager to host the list in plaintext format, then use a new AdBlockComponentFiltersProvider similar to the default filters provider to load the list in the browser. Unlike the default filters provider, however, this new provider will be registered with the AdBlockFiltersProviderManager so that it can be loaded into the additional_filters_engine_ rather than the default_engine_.