Migrate Streaming Expressions to the new Function Builder

[mkalkbrenner]

@wickedOne I wonder if we should leverage the function builder for streaming expressions.

[wickedOne]

i personally haven't used the streaming expression builder before, but at first glance and after a brief review of the documentation, it's usage looks fairly similar.

not sure whether we should incorporate both into one, but adopting it's pattern and usage sounds like a good idea to me!

first on my list is to finalise the query builder, but am more than happy to give it a go after that...