chore: Refactor cronjob controller

[hmalik88]

Refactors the CronjobController logic to deduplicate logic being used across cronjobs and background events.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 96.15385% with 1 line in your changes missing coverage. Please review.

Project coverage is 95.02%. Comparing base (4cd200d) to head (c059dd1). Report is 108 commits behind head on main.

Files with missing lines	Patch %	Lines
...snaps-controllers/src/cronjob/CronjobController.ts	96.15%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3029      +/-   ##
==========================================
+ Coverage   94.98%   95.02%   +0.03%     
==========================================
  Files         511      511              
  Lines       11313    11312       -1     
  Branches     1741     1742       +1     
==========================================
+ Hits        10746    10749       +3     
+ Misses        567      563       -4     

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[FrederikBolding]

Closing in favor of https://github.com/MetaMask/snaps/pull/3421