Add ID to entropy selector and invalid option for E2E testing

[Mrtenz]

I've made some minor changes to test-snaps related to the SIP-30 entropy selector.

• Each selector now has a unique ID. Previously the same ID was shared by multiple components, which is semantically incorrect HTML, and also makes it more difficult to E2E test.
• I've added an "invalid" option to the selector, to test that we properly throw errors for entropy sources that don't exist.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.93%. Comparing base (06798b3) to head (10fd543).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3172   +/-   ##
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  Coverage   94.93%   94.93%           
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  Files         507      507           
  Lines       11184    11184           
  Branches     1722     1722           
=======================================
  Hits        10618    10618           
  Misses        566      566           

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