fix: improve ability to control dynamo creds cache (#1870)

Exposes `AwsCredentialAdapter` for purpose of allowing its cache to be
used by the dynamo client.

This is necessary to get around a timeout loading credentials ...
Currently dynamo client default to lazy_builder

https://docs.rs/aws-sdk-dynamodb/0.34.0/src/aws_sdk_dynamodb/config.rs.html#790

This lazy cache has a 5 second timeout loading credentials:

https://github.com/smithy-lang/smithy-rs/blob/e78c60dbf169403eedceb1b718b862b0c5e5ee09/aws/rust-runtime/aws-credential-types/src/cache/lazy_caching.rs#L93

This change allows the caller to more easily pass their own
`ProvideCredentials` implementation and rely on the caching built into
`AwsCredentialAdapter`.

```rs
use aws_config::default_provider::credentials::DefaultCredentialsChain;
use aws_credential_types::provider::SharedCredentialsProvider;

use lance::dataset::ReadParams;
use lance_io::object_store::{AwsCredentialAdapter, ObjectStoreParams};
use vectordb::Database;

let creds_provider = Arc::new(AwsCredentialAdapter::new(
    Arc::new(SharedCredentialsProvider::new(DefaultCredentialsChain::builder().build().await)),
    ObjectStoreParams::default().s3_credentials_refresh_offset,
));

let db = Database::connect("s3://my-bucket/my-db?engine=ddb&ddbTableName=my-dyn-table").await.unwrap();
let table = db.open_table_with_params("my-table", ReadParams {
    store_options: Some(ObjectStoreParams {
        aws_credentials: Some(creds_provider),
        ..Default::default()
    }),
    ..ReadParams::default()
}).await.unwrap();

```

rust/lance-io/src/object_store.rs

@@ -108,7 +108,7 @@ const AWS_CREDS_CACHE_KEY: &str = "aws_credentials";
 
 /// Adapt an AWS SDK cred into object_store credentials
 #[derive(Debug)]
-struct AwsCredentialAdapter {
+pub struct AwsCredentialAdapter {
     pub inner: Arc<dyn ProvideCredentials>,
 
     // RefCell can't be shared accross threads, so we use HashMap
@@ -119,7 +119,10 @@ struct AwsCredentialAdapter {
 }
 
 impl AwsCredentialAdapter {
-    fn new(provider: Arc<dyn ProvideCredentials>, credentials_refresh_offset: Duration) -> Self {
+    pub fn new(
+        provider: Arc<dyn ProvideCredentials>,
+        credentials_refresh_offset: Duration,
+    ) -> Self {
         Self {
             inner: provider,
             cache: Arc::new(RwLock::new(HashMap::new())),

rust/lance-table/src/io/commit.rs

@@ -61,6 +61,7 @@ use lance_io::object_store::ObjectStoreParams;
 #[cfg(feature = "dynamodb")]
 use {
     self::external_manifest::{ExternalManifestCommitHandler, ExternalManifestStore},
+    aws_credential_types::cache::CredentialsCache,
     lance_io::object_store::{build_aws_credential, StorageOptions},
     object_store::aws::AmazonS3ConfigKey,
     std::borrow::Cow,
@@ -295,7 +296,10 @@ async fn build_dynamodb_external_store(
 
     let dynamodb_config = aws_sdk_dynamodb::config::Builder::new()
         .region(Some(Region::new(region.to_string())))
-        .credentials_provider(OSObjectStoreToAwsCredAdaptor(creds));
+        .credentials_provider(OSObjectStoreToAwsCredAdaptor(creds))
+        // caching should be handled by passed AwsCredentialProvider
+        .credentials_cache(CredentialsCache::no_caching());
+
     let dynamodb_config = match env::var("DYNAMODB_ENDPOINT") {
         Ok(endpoint) => dynamodb_config.endpoint_url(endpoint),
         _ => dynamodb_config,