build: docker multi-arch builds for x86 and arm

[iFergal]

This is a direct copy of @m00sey's keripy work in WebOfTrust/keripy#832 but for KERIA, hopefully no issues.

Adds arm docker builds and makes them available on the same tag for both architectures. (and resolves the re-publishing of old builds from --all-tags push)

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 93.71%. Comparing base (18d3ad7) to head (287b6f5). Report is 24 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #303 +/- ## ========================================== + Coverage 93.06% 93.71% +0.65% ========================================== Files 36 36 Lines 7121 7941 +820 ========================================== + Hits 6627 7442 +815 - Misses 494 499 +5 ```

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