This PR brings assertOps and assertResources sanitizers to Deno.test() API.
assertOps checks that test doesn't leak async ops, ie. there are no unresolved
promises originating from Deno APIs. Enabled by default, can be disabled using
Deno.TestDefinition.disableOpSanitizer.
assertResources checks that test doesn't leak resources, ie. all resources used
in test are closed. For example; if a file is opened during a test case it must be
explicitly closed before test case finishes. It's most useful for asynchronous
generators. Enabled by default, can be disabled using
Deno.TestDefinition.disableResourceSanitizer.
We've used those sanitizers in internal runtime tests and it proved very useful in
surfacing incorrect tests which resulted in interference between the tests.
All tests have been sanitized.
Closes #4208
For some reason, the unit tests for Deno.remove() were not being imported to
unit_tests.ts and, consequently, not being executed. Thus, I imported them,
refactored some existent ones and wrote new ones for the symlink removal case.
Since the creation of a symlink is not implemented for Windows yet, assertions
that consider this state were added when the tests are executed in this OS.
