Remove required dependencies from multi-ledger code

[andrewwhitehead]

Also adjusts the return value from get_ledger_for_identifier for consistency.

Fixes #1549

[swcurran]

@dbluhm -- can you please do the reviewing and testing of this, since you have the use case to try?

Others are welcome to jump in. A lot more code changed than expected :-).

[dbluhm]

@dbluhm -- can you please do the reviewing and testing of this, since you have the use case to try?

Others are welcome to jump in. A lot more code changed than expected :-).

Will do, thanks for working to address this one!

[codecov-commenter]

Codecov Report

Merging #1550 (04be014) into main (7422b3c) will increase coverage by 0.06%.
The diff coverage is 92.45%.

@@            Coverage Diff             @@
##             main    #1550      +/-   ##
==========================================
+ Coverage   95.69%   95.75%   +0.06%     
==========================================
  Files         527      527              
  Lines       32400    32306      -94     
==========================================
- Hits        31005    30936      -69     
+ Misses       1395     1370      -25     

[dbluhm]

I have confirmed that this fixes #1549. On top of that, the other changes for consistency look good.