By default, uses a 60 second timeout, backing off 2x each time (can be
overridden using the hidden `DENO_SLOW_TEST_TIMEOUT` which we implement
only really for spec testing.
```
Deno.test(async function test() {
await new Promise(r => setTimeout(r, 130_000));
});
```
```
$ target/debug/deno test /tmp/test_slow.ts
Check file:///tmp/test_slow.ts
running 1 test from ../../../../../../tmp/test_slow.ts
test ...'test' is running very slowly (1m0s)
'test' is running very slowly (2m0s)
ok (2m10s)
ok | 1 passed | 0 failed (2m10s)
```
---------
Signed-off-by: Matt Mastracci <matthew@mastracci.com>
Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>
