Added Complex Numbers keyboard to Calculator

[derekagorhom]

fixes (partially) #8013

This PR is ready for review

[derekagorhom]

I wanted to find out if this keyboard would have tooltips and also i found out that some keyboards on the calculator do not have tooltips

Maths keyboard
trunc, deg, sign, abs, exp, logit, logistic, atan2

Text/String keyboard
reverse

[rdstern]

@derekagorhom this is excellent and I am also really pleased that you are questioning more broadly - with your question on tooltips. (That is for later.)
As far as I have tested, it is working fine, so could be merged. But I suggest some minor changes, plus then (sorry) some more keys. It has become more important than I thought earlier.
a) Could you make complex as the second-to-last keyboard. I really like keeping the Integer keyboard as the last one.
b) In the Help it goes to Base R correctly. Even though there is really only that one package, could you use the drop-down control. Then users can see the name of the package - call it just Base, without necessarily going into it.
c) Now the extra keys! Most are copies from the maths keyboard, but there are 3 new ones. I am not sure why they are not also on the maths keyboard, but that is for another time!
I now wonder about this layout:

complex, real, imaginary, rad
mod, arg, conjugate, deg
exp, sin, cos, tan
log, sinh, cosh, tanh
sqrt, round, signif, pi

[derekagorhom]

@rdstern i have made the changes, can you review them
thanks

[rdstern]

@derekagorhom I am impressed. To me it is all ok.