fix(toolkit-lib): remove AsyncDisposable from Toolkit

[mrgrain]

BREAKING CHANGE: Remove the AsyncDisposable interface and dispose() method from the Toolkit class. These were previously unused and had no effect.

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.81%. Comparing base (3e8359c) to head (21adca7).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #312      +/-   ##
==========================================
+ Coverage   85.58%   85.81%   +0.22%     
==========================================
  Files         223      223              
  Lines       37002    37002              
  Branches     4493     4501       +8     
==========================================
+ Hits        31668    31752      +84     
+ Misses       5233     5160      -73     
+ Partials      101       90      -11     

Flag	Coverage Δ
suite.unit	85.81% <ø> (+0.22%)	⬆️

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