fix(toolkit-lib): drift detection options are unnecessarily required

[mrgrain]

Description

This PR improves the drift detection implementation in the CDK toolkit-lib by making the 'stacks' parameter optional in the DriftOptions interface and providing default options in the toolkit.drift() method. These changes enhance the API's usability and consistency.

Changes:

1. Made 'stacks' parameter optional in DriftOptions interface
2. Added default empty options object to toolkit.drift() method
3. Added a test case to verify that drift action can be invoked without options

These changes make the drift detection API more flexible and consistent with other toolkit methods that typically provide default options.

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.09%. Comparing base (f227c9b) to head (d550323).
Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #552   +/-   ##
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  Coverage   79.09%   79.09%           
=======================================
  Files          47       47           
  Lines        7074     7074           
  Branches      791      791           
=======================================
  Hits         5595     5595           
  Misses       1460     1460           
  Partials       19       19           

Flag	Coverage Δ
suite.unit	79.09% <ø> (ø)

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