Allow asserting, regardless of whether i.e. a Throwable is present

[jamietanna]

Current implementations expect full equality checks, including arguments, throwable, mdc`, etc to match.

One alternative is to create i.e.:

class NonCheckingThrowable extends Throwable {
  @Override
  public boolean equals(Object other) {
    return true;
  }
}

But this is not ideal - we should have some way of configuring this

[josephw]

Are you using assertEquals, and requiring a LoggingEvent that's going to partially match? Would you consider Hamcrest-style matchers instead:

assertThat(logEvent, messageMatches(...));

or AssertJ custom assertions:

assertThat(logEvent).hasMessageMatching(...);

? Those seem like something that could live in this, or a related, library.

[valfirst]

Fixed: #328