Add FirestoreRequestParamProcessor to fix database parameter typos in generated code#777

Copilot wants to merge 2 commits intomaingoogleapis/gapic-generator-php:mainfrom

copilot/fix-f773c73c-459c-4953-b261-7b0bae9f7861googleapis/gapic-generator-php:copilot/fix-f773c73c-459c-4953-b261-7b0bae9f7861Copy head branch name to clipboard