fix: appsmith ai app git import issue fixed (#37921)

## Description
This PR fixes the issue when trying to import git connected app which
has Appsmith AI plugin and query added.

Steps to test the fixes:
1. Create an app and connect it to git
2. Create appsmith ai plugin and add a query
3. Commit all the changes
4. In a new workspace, import this app from git, import should go
through successfully


Fixes #37833 
_or_  
Fixes `Issue URL`
> [!WARNING]  
> _If no issue exists, please create an issue first, and check with the
maintainers if the issue is valid._

## Automation

/ok-to-test tags="@tag.Datasource"

### 🔍 Cypress test results
<!-- This is an auto-generated comment: Cypress test results  -->
> [!TIP]
> 🟢 🟢 🟢 All cypress tests have passed! 🎉 🎉 🎉
> Workflow run:
<https://github.com/appsmithorg/appsmith/actions/runs/12142783624>
> Commit: f4c90b129022c328b667bf2e34fe9e635d6d0ce7
> <a
href="https://internal.appsmith.com/app/cypress-dashboard/rundetails-65890b3c81d7400d08fa9ee5?branch=master&workflowId=12142783624&attempt=2"
target="_blank">Cypress dashboard</a>.
> Tags: `@tag.Datasource`
> Spec:
> <hr>Tue, 03 Dec 2024 17:11:00 UTC
<!-- end of auto-generated comment: Cypress test results  -->


## Communication
Should the DevRel and Marketing teams inform users about this change?
- [ ] Yes
- [x] No


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Bug Fixes**
- Enhanced null safety checks in the `getFileIds` method to prevent
potential `NullPointerExceptions`.

- **Tests**
- Introduced unit tests for the `FileUtils` class to validate the
behavior of the `getFileIds` method under various conditions.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Co-authored-by: “sneha122” <“sneha@appsmith.com”>

app/server/appsmith-plugins/appsmithAiPlugin/src/main/java/com/external/plugins/utils/FileUtils.java

@@ -19,7 +19,8 @@ public class FileUtils {
     }
 
     public static List<String> getFileIds(DatasourceConfiguration datasourceConfiguration) {
-        if (datasourceConfiguration.getProperties() != null
+        if (datasourceConfiguration != null
+                && datasourceConfiguration.getProperties() != null
                 && datasourceConfiguration.getProperties().size() > 0) {
             for (Property property : datasourceConfiguration.getProperties()) {
                 if (property.getKey().equalsIgnoreCase(FILES)

app/server/appsmith-plugins/appsmithAiPlugin/src/test/java/com/external/plugins/services/FileUtilTest.java

@@ -0,0 +1,44 @@
+package com.external.plugins.services;
+
+import com.appsmith.external.models.DatasourceConfiguration;
+import com.appsmith.external.models.Property;
+import com.external.plugins.utils.FileUtils;
+import org.junit.jupiter.api.Test;
+import org.testcontainers.junit.jupiter.Testcontainers;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@Testcontainers
+public class FileUtilTest {
+    @Test
+    public void getFileIds_withNullDatasourceConfig_returnsEmptyList() {
+        DatasourceConfiguration datasourceConfiguration = null;
+        List<String> actualFileIds = FileUtils.getFileIds(datasourceConfiguration);
+        assertThat(actualFileIds).isEmpty();
+    }
+
+    @Test
+    public void getFileIds_withValidDatasourceConfig_returnsFileIdList() {
+        DatasourceConfiguration datasourceConfiguration = new DatasourceConfiguration();
+        datasourceConfiguration.setUrl("https://example.com");
+
+        // create file object
+        Map<String, Object> fileMap = new HashMap<String, Object>();
+        fileMap.put("id", "fileId");
+        fileMap.put("name", "fileName");
+        fileMap.put("size", 10);
+        fileMap.put("mimetype", "fileMimetype");
+
+        Property property = new Property();
+        property.setKey("Files");
+        property.setValue(List.of(fileMap));
+
+        datasourceConfiguration.setProperties(List.of(property));
+        List<String> actualFileIds = FileUtils.getFileIds(datasourceConfiguration);
+        assertThat(actualFileIds).contains("fileId");
+    }
+}