refactor: use one same base32 package

[gammazero]

Two separate base32 packages were used, whyrusleeping/base32 and multiformats/go-base32. This PR removes the dependency on whyrusleeping/base32 so that boxo only depends on one base32 package.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 63.88%. Comparing base (4794174) to head (2f51fc9).

@@            Coverage Diff             @@
##             main    #1192      +/-   ##
==========================================
+ Coverage   63.82%   63.88%   +0.06%     
==========================================
  Files         269      269              
  Lines       27115    27115              
==========================================
+ Hits        17306    17323      +17     
+ Misses       8092     8083       -9     
+ Partials     1717     1709       -8     

Files with missing lines	Coverage Δ
namesys/ipns_publisher.go	57.33% <ø> (ø)

... and 14 files with indirect coverage changes

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