feat(go,typescript,csharp): allowReserved parameter encoding; fix(go,java,python,ruby,php,csharp): nullable paginated request bodies; fix(python): streaming retry connection leak; fix(typescript): MCP process event listeners

feat(go,typescript,csharp): allowReserved parameter encoding; fix(go,java,python,ruby,php,csharp): nullable paginated request bodies; fix(python): streaming retry connection leak; fix(typescript): MCP process event listeners #4741