feat!: change default read_consistency_interval=5s (#2281)

Previously, when we loaded the next version of the table, we would block
all reads with a write lock. Now, we only do that if
`read_consistency_interval=0`. Otherwise, we load the next version
asynchronously in the background. This should mean that
`read_consistency_interval > 0` won't have a meaningful impact on
latency.

Along with this change, I felt it was safe to change the default
consistency interval to 5 seconds. The current default is `None`, which
means we will **never** check for a new version by default. I think that
default is contrary to most users expectations.

nodejs/src/connection.rs

@@ -48,8 +48,16 @@ impl Connection {
     pub async fn new(uri: String, options: ConnectionOptions) -> napi::Result<Self> {
         let mut builder = ConnectBuilder::new(&uri);
         if let Some(interval) = options.read_consistency_interval {
-            builder =
-                builder.read_consistency_interval(std::time::Duration::from_secs_f64(interval));
+            match interval {
+                Either::A(seconds) => {
+                    builder = builder.read_consistency_interval(Some(
+                        std::time::Duration::from_secs_f64(seconds),
+                    ));
+                }
+                Either::B(_) => {
+                    builder = builder.read_consistency_interval(None);
+                }
+            }
         }
         if let Some(storage_options) = options.storage_options {
             for (key, value) in storage_options {