Minitest/AssertMatch behavior doesn't match style guide

[vlad-pisanov]

Currently, the style guide for Minitest/AssertMatch says:

# bad
assert(pattern.match?(object))
# good
assert_match(pattern, object)

However, the cop detects a different pattern:

assert(pattern.match(object))

Ideally, it should detect all of these variants:

assert(pattern.match(object))
assert(pattern.match?(object))
assert(object =~ pattern)