Shorter message for simple assertion failures

**Is your feature request related to a problem? Please describe.**

I use `assertEquals` quite often in my tests When running from VSCode, I get this little tooltip


which can be clicked on to get the full error message


**Describe the solution you'd like**

I wish I didn't always have to click on the message. It'd be lovely if it would display a variation of the following for *short* messages



This is actually pretty straightforward to implement. It's roughly
```
let message;
if (actualString.length + expectedString.length <= 32) {
message = `${actualString} != ${expectedString}${msgSuffix}`;
} else {
message = `Values are not equal${msgSuffix}`;
}
```

**Describe alternatives you've considered**

- Write my own `assertEquals`.

- Just accept the one extra click.

- Hook up the `expected` and `actual` values in the Deno LSP and report it to the UI that way. Part of the code for that is already in the LSP.