refactor!: Pass executor parameters by object

[FrederikBolding]

Refactor BaseSnapExecutor to expect parameters to always be passed by object. We were already passing the parameters by object in production, but then internally converting them to an array. This made typing harder and generally isn't necessary. We can now more easily validate the parameters and correctly narrow the types, reducing the casting required. The PR also refactors the handling of incoming command requests a bit to become more readable. Theoretically this should also make the executor a bit faster at processing commands.

This PR is breaking as now only passing by object is allowed.

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Note

Medium Risk
Medium risk because it changes the internal JSON-RPC command contract for executeSnap/snapRpc (array params no longer accepted) and refactors command dispatch/validation in the snap execution environment, which could break any remaining callers still using positional params.

Overview
Breaking change: executor command RPCs now require named object params (no positional arrays). executeSnap takes { snapId, sourceCode, endowments } and snapRpc takes { snapId, handler, origin, request }; snapRpc also drops the old target field.

BaseSnapExecutor command handling is refactored to a switch-based dispatcher with centralized param validation (assertCommandParams), removing the old param-sorting/command-implementation helpers. Tests and test utilities across browser/iframe/node execution environments are updated accordingly, and coverage expectations are adjusted.

^{Written by Cursor Bugbot for commit edee29c. This will update automatically on new commits. Configure here.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.46%. Comparing base (07d1937) to head (edee29c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3803      +/-   ##
==========================================
+ Coverage   98.39%   98.46%   +0.07%     
==========================================
  Files         430      429       -1     
  Lines       12457    12395      -62     
  Branches     1932     1922      -10     
==========================================
- Hits        12257    12205      -52     
+ Misses        200      190      -10     

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Cursor Bugbot has reviewed your changes and found 2 potential issues.