Add studentTTestOneSample aggregate

Why it matters

This feature introduces the studentTTestOneSample aggregate function to perform one-sample Student's t-tests within ClickHouse. It enables users to statistically test whether the mean of a sample differs significantly from a given value, providing essential hypothesis testing capabilities directly in SQL queries.

How to use it

Use the studentTTestOneSample aggregate function in your queries by passing the sample values and the hypothesized population mean. For example:

SELECT studentTTestOneSample(sample_column, hypothesized_mean) FROM table;