Draft: feat: Count blocking log items for facebook.com [EE-412]

Here we listen for EWE.reporting.onBlockableItem, filter tracked domains, save the entries in local (b.s.l) storage and expose some API to request and clear.

Few questions:

• do we assume the country stays the same. Could/should we optimize: don't detect it every time a log item is emitted, but do it once the SW starts for instance?
• should we track subdomains
• how do we detect network level

Design questions:

• is it ok to reuse modified TabSessionStorage (modified to save in different storages) or it's better to have a dedicated data structure?
• should we optimize for space (saving domain property for every entry, but actually we can recover it from domain id used as a key)?
• shouldn't we adapt Map() to have the same API as browser storage in order to avoid having alternative flows for in-memory map?