Pause timer on fetch

[FrederikBolding]

This PR adds notifications from the network access endowment that are sent during fetch. Calling fetch will result in OutboundRequest upfront and OutboundResponse once the promise resolves. Furthermore, once per response object, triggering an async action, e.g. json() will also trigger OutboundRequest upfront and OutboundResponse once the promise resolves. The notifications pause the request processing timer in the same way that requests via snap.request and ethereum.request pause the timer.

This PR also refactors the endowment creation slightly to make it take an options bag and always require an endowment array.

Closes #1755

[codecov]

Codecov Report

Attention: 10 lines in your changes are missing coverage. Please review.

Comparison is base (27fe061) 96.15% compared to head (1a59233) 96.03%.

Files	Patch %	Lines
...tion-environments/src/common/endowments/network.ts	85.29%	10 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1756      +/-   ##
==========================================
- Coverage   96.15%   96.03%   -0.12%     
==========================================
  Files         263      263              
  Lines        6086     6129      +43     
  Branches      989      991       +2     
==========================================
+ Hits         5852     5886      +34     
- Misses        234      243       +9     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.