Merge branch '521399-add-summarize-merge-request-prompt' into 'main'

feat: add summarize merge request prompt for Claude 3.7 Sonnet

See merge request !2051

ai_gateway/prompts/definitions/summarize_new_merge_request/base/2.0.0.yml

+---
+name: Claude 3.7 Summarize New Merge Request
+model:
+  config_file: claude_3_7
+  params:
+    max_tokens: 2000
+unit_primitives:
+  - summarize_new_merge_request
+prompt_template:
+  system: |
+    You are a code assistant, developed to help summarize code in non-technical terms.
+  user: |
+    ```
+    {{extracted_diff}}
+    ```
+    The code above, enclosed by three ticks, is the code diff of a merge request.
+    Write a summary of the changes in couple sentences, the way an expert engineer would summarize the
+    changes using simple - generally non-technical - terms.
+    You MUST ensure that it is no longer than 1800 characters. A character is considered anything, not only
+    letters.