Dynamic ledger managed tasks

[sug0]

Describe your changes

Closes #459

Refactors the ledger boot-up code under run_aux, to support a dynamic number of managed tasks.

Checklist before merging

• If this PR has some consensus breaking changes, I added the corresponding breaking:: labels
  • This will require 2 reviewers to approve the changes

[codecov]

Codecov Report

Attention: Patch coverage is 70.03891% with 77 lines in your changes missing coverage. Please review.

Project coverage is 71.78%. Comparing base (9139dbe) to head (233378b).
Report is 10 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/node/src/lib.rs	0.00%	39 Missing ⚠️
crates/node/src/ethereum_oracle/mod.rs	0.00%	25 Missing ⚠️
crates/node/src/abortable.rs	93.26%	13 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3741      +/-   ##
==========================================
+ Coverage   71.66%   71.78%   +0.12%     
==========================================
  Files         311      311              
  Lines      101508   101658     +150     
==========================================
+ Hits        72748    72980     +232     
+ Misses      28760    28678      -82     

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[sug0]

I'll add a couple of tests to this branch before merging