feat(toolkit): add a return type for toolkit.deploy()

[rix0rrr]

toolkit.deploy() now returns information about the stacks it deployed.

Fixes aws/aws-cdk#33189

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.95%. Comparing base (2df3633) to head (f319a19).
Report is 202 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #317      +/-   ##
==========================================
+ Coverage   86.70%   86.95%   +0.24%     
==========================================
  Files         220      220              
  Lines       35643    35648       +5     
  Branches     4344     4346       +2     
==========================================
+ Hits        30906    30999      +93     
+ Misses       4644     4550      -94     
- Partials       93       99       +6     

Flag	Coverage Δ
suite.unit	86.95% <100.00%> (+0.24%)	⬆️

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