fix: Support testing nested argument method signatures and 'double' field assertions

[burkedavison]

• Handle method signatures with nested arguments.

  Before:

  Assert.assertEquals(displayName, actualRequest.getDisplayName());

  After:

  Assert.assertEquals(displayName, actualRequest.getUser().getDisplayName());

• Provide a consistent tolerance value of 0.0001 for assertEquals on double and float values.

  Before:

  Assert.assertEquals(expected, actual);

  bazel error: [DoNotCall] This method always throws java.lang.AssertionError. Use assertEquals(expected, actual, delta) to compare floating-point numbers

  After:

  Assert.assertEquals(expected, actual, 0.0001);

[sonarqubecloud]

SonarCloud Quality Gate failed.   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

76.7% Coverage
0.0% Duplication

[blakeli0]

Ideally for every composer change, we should have a golden unit test updated, like this one. But since we know it will be tested as part of the showcase integration tests, and we are moving away from generated unit tests, this PR is good to merge.