feat: add of() method to fetch NIP-05 data without pubkey

[nogringo]

ndk.nip05.of("pubkey") never read from cache. Do we need update cache managers with a method to get the pubkey from the nip05 idetifier ?

Close #208

[codecov]

Codecov Report

❌ Patch coverage is 97.50000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 72.47%. Comparing base (07dfd2c) to head (c22a1e4).
⚠️ Report is 18 commits behind head on master.

Files with missing lines	Patch %	Lines
packages/ndk/lib/presentation_layer/ndk.dart	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #382      +/-   ##
==========================================
+ Coverage   72.30%   72.47%   +0.17%     
==========================================
  Files         144      144              
  Lines        5585     5620      +35     
==========================================
+ Hits         4038     4073      +35     
  Misses       1547     1547              

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