…ions in NewDatabase

Add a new database constructor NewDatabaseWithOptions to allow passing arbitrary user-specified grpc dial options.

This is useful for constructs like
```go
driver := flightsql.NewDriver(memory.DefaultAllocator)
driver.NewDatabaseWithOptions(map[string]string{
		"uri": uri,
	},
	grpc.WithStatsHandler(otelgrpc.NewClientHandler())
)
```

which allows usage of the opentelemetry grpc instrumentation for example.

This also provides an escape valve for users that need the ability to use less commonly used grpc client features that we have not exposed via the string map args.