encoding: Better support for address encodings.

[winder]

Summary

There is a bug in the newer version of Indexer used by Conduit which caused addresses to be encoded differently. This PR makes the decoding more lenient to allow for the different encodings.

Test Plan

New unit test.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (hotfix/2.15.4@a700bdd). Click here to learn what that means.
The diff coverage is 90.47%.

@@               Coverage Diff                @@
##             hotfix/2.15.4    #1531   +/-   ##
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  Coverage                 ?   65.24%           
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  Files                    ?       52           
  Lines                    ?     8375           
  Branches                 ?        0           
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  Hits                     ?     5464           
  Misses                   ?     2436           
  Partials                 ?      475           

Impacted Files	Coverage Δ
idb/postgres/internal/encoding/types.go	66.66% <ø> (ø)
idb/postgres/internal/encoding/encoding.go	89.43% <90.47%> (ø)

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[algochoi]

Changes look fine but do we need to cherry-pick fixes to this hotfix branch everytime? I'm not familiar with this dual branch system.

edit: Oh is this the legacy indexer? I guess that makes more sense

[shiqizng]

this looks good. I'm starting an indexer deployment to verify that it works as expected.

[winder]

Changes look fine but do we need to cherry-pick fixes to this hotfix branch everytime? I'm not familiar with this dual branch system.

@algochoi This is for the next release. It's a gitflow thing, but also a little strange because of the licensing work currently staged in develop.

[algochoi]

Looks like it was correctly copied

[winder]

Confirmed regression fix with mainnet data.

Scenario: Initialize postgres DB using Conduit master branch and a mainnet follower node.

Indexer running the current tip of master: 1c79c90 reproduces the encoding error

$ curl localhost:10000/v2/blocks/20215865?pretty
{
  "message": "error while looking up block for round '20215865': json decode error [pos 641]: failed to decode address 2GpQYYQK6VSxGFumcF/wZ4OLnJDJTASMIG5VL/AyU4k= to base 32"
}

This PR applied to the hotfix/2.15.4 branch: 8d6161b is able to fetch the data.

$ curl -s localhost:10000/v2/blocks/20215865?pretty|grep part
  "participation-updates": {
    "expired-participation-accounts": [