Client Interface: Generate Overloads for scalar values

[AlexanderViand-Intel]

Simple convenience, so that you can say "encrypt(x)" for scalar "x" and have the generated function do the replication for you. We already emit code that'll take vectors of the wrong length and repeat/pad them to the required size so this should be a straightforward extension.

[j2kun]

In my increasingly expanding #1633 I am finding the need to support layout assignment for scalars as well, so this could be reused on the client side step.