Use JUnit5's assertSame or assertNotSame instead of assertTrue(... == ...)

[mccartney]

What's changed?

Adding a new recipe for converting:

assertTrue(a == b);

to

assertSame(a, b);

for JUnit5 test code as suggested in

• Transform assertTrue to assertSame or assertNotSame #260

Checklist

• I've added unit tests to cover both positive and negative cases
• I've read and applied the recipe conventions and best practices
• I've used the IntelliJ IDEA auto-formatter on affected files

[timtebeek]

Thanks @mccartney ! I've applied a few small polishing commits, such as visiting method invocations directly, as opposed to via method declarations, to match cases nested in assertAll for instance. We'll also want to update the method type, as chained assertions look at the type, not the simple name.