fix(share): left pad nid in NewNamespaceV0 instead of right padding

[distractedm1nd]

Closes #2320

[Wondertan]

Once we are on it and there is no rush, let's add a unit test that confirms that we correctly left pad it. The example in the issue would be the best.

[distractedm1nd]

Added unit tests and improved docs

[codecov-commenter]

Codecov Report

Merging #2341 (ea0b9f2) into main (ae8db72) will increase coverage by 0.09%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #2341      +/-   ##
==========================================
+ Coverage   50.84%   50.94%   +0.09%     
==========================================
  Files         154      154              
  Lines        9743     9744       +1     
==========================================
+ Hits         4954     4964      +10     
+ Misses       4358     4347      -11     
- Partials      431      433       +2     

Impacted Files	Coverage Δ
share/nid.go	76.92% <100.00%> (+76.92%)	⬆️

... and 3 files with indirect coverage changes