ledger-tool: Condense repeated error handling

[steviez]

This PR is a split out from #34426

Problem

Several commands call load_and_process_ledger() which can fail in a number of ways. These callers currently all handle the result in the same way by matching the return Result:

• The Ok(_) case uses the returned types as normal
• The Err(_) case prints an error message and exits

This error handling is redundant, and a helper could remove the duplicate code

Summary of Changes

• Introduce load_and_process_ledger_or_exit(), a wrapper for load_and_process_ledger() that unwraps OR prints an error message and returns for Err
• Use the new load_and_process_ledger_or_exit() in all previous callers of load_and_process_ledger()
• Run cargo fmt to remove the level of indentation from previous callers

[codecov]

Codecov Report

Merging #34439 (5539739) into master (a04ab94) will increase coverage by 0.0%.
Report is 5 commits behind head on master.
The diff coverage is 100.0%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #34439   +/-   ##
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  Coverage    81.8%    81.9%           
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  Files         819      819           
  Lines      220936   220931    -5     
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+ Hits       180936   180955   +19     
+ Misses      40000    39976   -24     

[brooksprumo]

lgtm