Math: Implement `sqrt`

[certik]

Original issue: https://gitlab.com/lfortran/lfortran/-/issues/468

Needed for https://gitlab.com/lfortran/lfortran/-/issues/401.

Definition

As per J3/18-007r1 (the F2018 Interpretation Document):

Example

Simple sample:

program intrinsics_08
real :: x

x = sqrt(0.76159416)
print *, x

end

Standard

Note that the relevant standard can be found here: 18-007r1.pdf

[konradha]

I tested this a little, this can be considered done, right @certik ?

[HarshitaKalani]

I believe this is resolved already.

[certik]

Yes, sqrt works. Although it should be ported to use IntrinsicFunction.