Outer Joins in Flux

The Flux query team has developed a new join package to improve upon existing solutions and provide support for outer joins, which was a frequently requested feature. The new package provides six functions, including `tables()`, `inner()`, `full()`, `left()`, `right()`, and `time()`, with the latter three being aliases for the first three. It allows users to define left and right input table streams and compare records from these tables based on a function that takes two records as arguments, following a specific format. The package also supports different join methods, including inner, left, right, and full joins, each with its own set of rules for constructing the output record. The new package aims to improve performance by reducing row comparisons and provide flexibility in join predicates, which can be used to leverage complex comparisons in the future.