token: fix transfer to self

[Fraccaman]

Describe your changes

To make things easier, lets make transfer fails if source == dest

Checklist before merging

• If this PR has some consensus breaking changes, I added the corresponding breaking:: labels
  • This will require 2 reviewers to approve the changes

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.18%. Comparing base (b7d2db3) to head (f5268cd).
Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3675      +/-   ##
==========================================
+ Coverage   61.12%   61.18%   +0.05%     
==========================================
  Files         315      315              
  Lines      103056   103168     +112     
==========================================
+ Hits        62994    63121     +127     
+ Misses      40062    40047      -15     

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[tzemanovic]

the transfer to self has to be a no-op cause it's used from protocol where it shouldn't fail otherwise a tx might get wrongly rejected