Create new metrics-lib package with generally useful classes and functions

This ticket is based on a discussion on legacy/trac#24036 (moved):

• At some point in the future we may add a new package org.torproject.metrics.util with generally useful classes and functions, including fingerprint calculations and commonly used regular expressions.

added component::metrics/library in Legacy / Trac owner::metrics-team in Legacy / Trac priority::medium in Legacy / Trac severity::normal in Legacy / Trac status::new in Legacy / Trac type::enhancement in Legacy / Trac labels

moved from legacy/trac#24293 (moved)

added Feature label and removed 1 deleted label

removed 1 deleted label

closed