Fix redundant JUnit TestCase constructors and their callers across source files.

[motlin]

What's changed?

MigrateJUnitTestCase now scans constructor declarations and references before removing redundant TestCase(String) constructors. Calls such as new MathTest("FOO") become new MathTest(), including callers in other source files. The change also follows redundant superclass constructor chains and updates super(...) and this(...) calls.

What's your motivation?

• Fixes MigrateJUnitTestCase removes the TestCase(String) constructor without updating its callers, breaking compilation #1107. Removing a constructor without updating its callers leaves migrated tests unable to compile, including subclasses that still call the removed base constructor.

Anything in particular you'd like reviewers to focus on?

• Please review the cross-file constructor matching and propagation through inheritance and delegation chains. This change addresses redundant constructors; initialization in retained constructors is covered separately by A retained TestCase(String) constructor leaves the migrated test class unrunnable under JUnit 5 #1108.