Add the clamp() algorithm

[zolkis]

This is to track the algorithm specification for the clamp() operation.
Depends on #336.

[zolkis]

What needs discussion:

• This is one of those ops that may return an operator (nowadays MLActivation) or an MLOperand. Check if the steps are appropriately formulated.
• Dependency on MLActivation constructor (with an MLOperand input, output and the op name).
• Dependency on MLOperand internal slot (of type MLOperandDescriptor).

[inexorabletash]

I believe this is complete. Marking closed, if anything is still outstanding please re-open or file a new issue with the details.