DynamoDB enhanced client silently fails when necessary extensions are not installed + exposes no list of installed extensions

### Describe the bug

I learned the hard way that if the `VersionedRecordExtension` is not installed on my instance of `DynamoDbEnhancedClient`, the client silently ignores `DynamoDbVersionAttribute` annotations, stops performing optimistic locking, and writes null versions to the database. There is no compile time or run time check for missing extensions.

### Regression Issue

- [ ] Select this option if this issue appears to be a regression.

### Expected Behavior

I expected the client to provide a fast-fail mechanism of some kind if necessary extensions are not installed to support the annotations used in a `DynamoDbBean` entity definition. At the very least, it would be ideal if the `DynamoDbEnhancedClient` instances exposed a list of installed extensions so callers could implement their own fast-fail logic.

### Current Behavior

The `DynamoDbEnhancedClient` quietly ignores annotations that are not supported by its list of installed extensions.

### Reproduction Steps

The following code snippets can be used to write a record to Dynamo that should have a version field populated with the value `1`. Instead, it will have no value for this field.

Entity definition (Kotlin)

```kotlin
@DynamoDbBean
data class MyEntity(
@get:DynamoDbPartitionKey
@get:DynamoDbAttribute("pk")
var pk: String = "",
// Sort Key, should always be "LOAN" unless we introduce new types of records,
// which would probably be represented by different classes.
@get:DynamoDbSortKey
@get:DynamoDbAttribute("sk")
var recordType: String = "",

@get:DynamoDbVersionAttribute
@get:DynamoDbAttribute("version")
var version: Int? = null,
)
```

Client setup (Java):

```java
var client = DynamoDbEnhancedClient.builder()
.dynamoDbClient(DynamoDbClient.builder().build())
.extensions(List.of()) // Some list of extensions that causes record versioning extension not to be installed
.build();
```

Usage of table (Kotlin):

```kotlin
val table = client.table("my-table", TableSchema.fromBean(MyEntity::class.java))
val record = MyEntity(
pk = "some-pk",
sk = "some-sk"
)
table.putItem(PutItemEnhancedRequest.builder(MyEntity::class.java)
.item(record)
.build())
```

### Possible Solution

At a minimum, if the enhanced client object could provide a public list of extensions installed, callers could add start-up logic in their applications to assert that expected extensions are there.

### Additional Information/Context

_No response_

### AWS Java SDK version used

2.31.54

### JDK version used

21.0.4

### Operating System and version

MacBook Pro, Apple M2 Max, Sequoia 15.5