This commit adds support for running test in parallel.
Entire test runner functionality has been rewritten
from JavaScript to Rust and a set of ops was added to support reporting in Rust.
A new "--jobs" flag was added to "deno test" that allows to configure
how many threads will be used. When given no value it defaults to 2.
This commits adds adds "permissions" option to the test definitions
which allows tests to run with different permission sets than
the process's permission.
The change will only be in effect within the test function, once the
test has completed the original process permission set is restored.
Test permissions cannot exceed the process's permission.
You can only narrow or drop permissions, failure to acquire a
permission results in an error being thrown and the test case will fail.
