Feature request: omit printing the assertions

[Sorokin-Anton]

If I do multiple Alcotest.check and one of them fails (or Alcotest.fail happened), I see [ASSERT] messages related to other checks. There are several reasons why I don't like this behavior and want a way to disable show_assert:

• I suppose message string to appear in case of assertion fail, so I write something like "type does not match expected for ..." and seeing this messages when other thing is wrong may be confusing
• I can do many checks in one tests, and I don't want to have hundreds of assertions in CI log, I want just the failure message
• Even with one check, I see the same message twice - with [ASSERT] and [FAIL], that does not look cool