Update on "[ET][Portable][Build Size] Introduce uni-tensor and bi-tensor equivalents"

This introduces unitensor and bitensor equivalents to the tritensor template introduced by swolchok.
They are applied to add.Scalar_out and add.out respectively, reducing op_add's build size.
The unitensor template is applied to clamp.Scalar_out, reducing op_clamp's build size further.

Build size reduction:
- add: 484K -> 21K
- clamp: 119K -> 28K

Differential Revision: [D63838076](https://our.internmc.facebook.com/intern/diff/D63838076/)

[ghstack-poisoned]

Author: manuelcandales