fix-25: remove the previous nft owner if balance=0

[fforbeck]

Proposed Changes

• Fixed the _nftTracker and _ownership mappings to remove the correct account when an NFT is moved out of the extension contract.

[codecov]

Codecov Report

Merging #515 (5d8e8d3) into master (d83470d) will increase coverage by 0.38%.
The diff coverage is 100.00%.

❗ Current head 5d8e8d3 differs from pull request most recent head 8a80c51. Consider uploading reports for the commit 8a80c51 to get more accurate results

@@            Coverage Diff             @@
##           master     #515      +/-   ##
==========================================
+ Coverage   83.28%   83.67%   +0.38%     
==========================================
  Files          53       53              
  Lines        1855     1856       +1     
  Branches      431      431              
==========================================
+ Hits         1545     1553       +8     
+ Misses        310      303       -7     

Impacted Files	Coverage Δ
contracts/adapters/KycOnboarding.sol	93.33% <100.00%> (ø)
...racts/extensions/erc1155/ERC1155TokenExtension.sol	97.22% <100.00%> (+9.72%)	⬆️
contracts/test/ERC1155TestAdapter.sol	100.00% <100.00%> (ø)

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