Add an "expect" type of function connected to logging infrastructure

[mkorbel1]

Motivation

When you write tests in Dart, you can use things like expect to ensure something is true or else fail the test. In ROHD-VF, the preferred mechanism is to use logger.severe or logger.shout (or as configured for error/fatal) instead. This allows the test to not immediately fail out, resulting in things like continuing on error, not corrupting the VCD file generated for waves, etc. However, this results in a pattern difference from:

expect(a, 1);

to:

if(a != 1) {
  logger.severe('a must be 1');
}

It would be nice if we had a mechanism built-in to ROHD-VF that was similar to expect.

Desired solution

Add some functions to ROHD-VF that "feel" more like expect

Alternatives considered

No response

Additional details

No response