Fix ignored insecure option and add unit and integration tests

[dantasse]

This PR lets us use TLS (accidentally(?) ignored before) and adds a bunch of tests.

Bug fix: insecure was ignored

ClientOptions.insecure was documented but never read. The Flight client always created plaintext credentials, so TLS connections could not work. Connections now use TLS by default and plaintext only when insecure: true is passed, which is what the docs always said.

Breaking change: anyone connecting to a plaintext server without insecure: true will now fail the TLS handshake. The README calls this out. No merged code in LanceDB depends on this package yet, so nothing released needs to absorb it.

Also fixed: getFlightInfo called resolve after reject on the error path.

Tests

Added ~50 unit tests and 8 integration tests. Integration tests (more valuable imo) include: bad credentials, invalid SQL, empty result sets, a full multi-batch read checked against COUNT(*), type mapping across ten SQL types, early exit from a stream, a concurrent burst, and importing the published package from an ES module.

[westonpace]

Yes, we probably need this. My only concern is that this is implemented as a backwards incompatible change. There are a few users of this library and these users would suddenly break without warning.

Could we start with the default of insecure=true? We could log a warning if the user doesn't specifically set insecure saying the default will be changing soon and they should explicitly set a value to disable the warning and then change it in a future release?

[westonpace]

Is this a backwards incompatible change? Was the previous default that we didn't use TLS?

[dantasse]

oh right! yeah I didn't know this had users. makes perfect sense.

In the past:

• TLS was always off. insecure was an option but didn't actually do anything.
• Docs implied that TLS was on by default. (didn't really say so explicitly, but just the docstring on insecure said Is the server using TLS? If not, this must be set to true.)

So a current user might assume either that TLS is on by default or off by default 😅
But I agree with your instinct that it's better to match old behavior than old docs. So I've switched the default to be insecure=true.