A function `corrMatrix` to calculate correlation across all the pairs of arguments.

**Use case**

See https://github.com/ClickHouse/ClickHouse/issues/35979

**Describe the solution you'd like**

Let's add a function `corrMatrix`, taking an arbitrary number of arguments and returning a 2d array.
Note: this matrix will be somewhat redundant - symmetric with 1 on the diagonal, but let's return it as a whole for simplicity.