746 tests vdataframe math and rolling

[vikash018]

UT code for math and rolling functions.

Two observations:

1. log function in apply_fun - Expected log arg from vertica doc is log (base, expression). However, Verticapy is considering log (expression, base) i.e. in reverse order.

titanic["age"].apply_fun(func = "log")

2. mad (median absolute deviation) function in analytic is using mean instead of median.
   titanic.analytic(func="mad", columns="age", name="mad")

[oualib]

Creating another PR to solve the two issues.