feat: Allow async initialization logic

[FrederikBolding]

Allow async initialization logic for Snaps by altering the CLI config to do direct assignment of the exports to module.exports. This lets Snap developers use async initialization logic such as top-level await (which has been re-enabled) and asynchronous instantiation of WASM modules (which has been introduced in favor of sync). A minor change was also made to the execution environment to await the exposed module after evaluating it.

Snaps are still subject to a 60 second initialization timeout, so the asynchronous logic must finish before that timer runs out.

Closes #2919
Closes #2359

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.49%. Comparing base (f1d3cd6) to head (bd2e1dd).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2918   +/-   ##
=======================================
  Coverage   94.49%   94.49%           
=======================================
  Files         487      487           
  Lines       10441    10442    +1     
  Branches     1600     1600           
=======================================
+ Hits         9866     9867    +1     
  Misses        575      575           

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