Optimization: Add member and API to store solver-specific data
Optimization: Add member and API to store solver-specific data

Allow solvers to store data that persists across runs to avoid repeating
memory allocation on every call.

GitHub-Issue: #1667

sheim/drake,billhoffman/drake,sheim/drake,billhoffman/drake,billhoffman/drake,billhoffman/drake,billhoffman/drake,psiorx/drake,psiorx/drake,psiorx/drake,sheim/drake,sheim/drake,psiorx/drake,psiorx/drake,billhoffman/drake,sheim/drake,sheim/drake,billhoffman/drake,sheim/drake,sheim/drake,billhoffman/drake,psiorx/drake,psiorx/drake,psiorx/drake