zip_open/ZipArchive should throw an exception in CLI server mode unless opening read-only

**Describe the bug**

https://github.com/facebook/hhvm/blob/908da97341f8d4b65bd19884489a4e8a1adaaa98/hphp/runtime/ext/zip/ext_zip.cpp#L45 attempts to set the appropriate flags for various modes in CLI server, however they will never work:

https://libzip.org/documentation/zip_fdopen.html

> In contrast to [zip_open(3)](https://libzip.org/documentation/zip_open.html), using zip_fdopen the archive can only be opened in read-only mode.

zip_open can't directly be used here because it would be a privilege escalation bug.

I think a 'real fix' would be making the CLI client process capable of high-level zip operations, but a clear 'unsupported in CLI server mode' exception would make debugging issues much simpler.

**Standalone code, or other way to reproduce the problem**

**IN CLI SERVER MODE**

```
$z = new ZipArchive();
$z->open('/tmp/foo.zip', ZIPARCHIVE::CREATE); // ALWAYS fails
```

**Expected behavior**

Ideally, it works, opening the zip as the CLI client user.
Better would be a clear exception saying why it will always fail

**Actual behavior**

open fails, invalid zip