chore(ai): add prompt to upgrade tests file

Author: xperiandri

.github/prompts/process-tests-file.prompt.md

@@ -0,0 +1,7 @@
+---
+mode: agent
+
+tools: ['githubRepo', 'github', 'get_me', 'get_commit', 'get_file_contents', 'get_pull_request', 'get_pull_request_diff', 'get_pull_request_files', 'get_tag', 'list_branches', 'list_commits', 'list_tags', 'search_code', 'search_issues', 'search_repositories', 'microsoft_docs_search'] 
+---
+
+Examine tests from the other collections with the same name and in the current file implement missing tests and remove irrelevant