swift

e342c1fe - Add `-enable-experimental-differentiable-programming` frontend flag. (#27445)

Add `-enable-experimental-differentiable-programming` frontend flag. (#27445) This flag will enable all differentiable programming features. The default will be `true` on tensorflow branch but `false` on master branch. Features will first be updated on tensorflow branch to use this flag, before being upstreamed to master. The goal is to achieve a minimal code diff between the two branches. TF-820 tracks upstreaming differentiable programming.