feature request: abs for param complex

[mppf]

Summary of Problem

abs on a param complex number does not produce a param, but I would expect it to.

In order to implement this, we will a need param-time sqrt for real numbers. That should also be available to users.

Steps to Reproduce

Source Code:

param c:complex(128) = 1.0i;    
param x = abs(c); // error: Initializing parameter 'x' to value not known at compile time

Associated Future Test(s):

test/library/standard/AutoMath/absparamscomplex.chpl #24127

[damianmoz]

Not urgent.