Add rules to distribute conj over sum and prod

[benneti]

distributing conj makes it easier to apply the remaining rules

[benneti]

As this is my first PR in this repo pointers are very welcome.
To slighly expand on my thinking here: at the moment complex conjugating a longer expression including real variables stops the simplification. In a lot of cases this simplification would avoid this.
A very simple example @syms x::Real y::Number; conj(x*y)*x*y |> simplify which could not be simplified before an now becomes (x^2)*y*conj(y).

For me locally rulesets tests are all green.