[Access] Validate checkpoint's root hash

[peterargue]

Closes: #4806

This PR updates the Access node's register db checkpoint loader to verify the root hash from the checkpoint matches the root hash from the protocol state.

It also removes configuration to specify the checkpoint height since it is assume (and verified) to be the root block.

[codecov-commenter]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (ac256c1) 55.85% compared to head (b203b00) 55.88%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4830      +/-   ##
==========================================
+ Coverage   55.85%   55.88%   +0.03%     
==========================================
  Files         944      944              
  Lines       87767    87778      +11     
==========================================
+ Hits        49022    49057      +35     
+ Misses      35056    35030      -26     
- Partials     3689     3691       +2     

Flag	Coverage Δ
unittests	55.88% <75.00%> (+0.03%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
...dule/state_synchronization/indexer/indexer_core.go	88.07% <100.00%> (+0.66%)	⬆️
module/metrics/noop.go	0.00% <0.00%> (ø)
module/metrics/execution_state_indexer.go	0.00% <0.00%> (ø)

... and 11 files with indirect coverage changes

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