Move builder_util into builder itself

[anshumanmohan]

Quoting Adrian from #1630:

I have an idea for how to make this API even more pleasant to use. Instead of top-level functions that take a ComponentBuilder as an argument, we could wrap the underlying ComponentBuilder (one way or another) and provide these as methods. The methods could then have shorter names too. So using the API would look more like comp.eq(a, b) instead of insert_eq(comp, a, b).

The options include:

1. Move all of these into ComponentBuilder. Easy peasy, if not exactly organized.
2. Subclass ComponentBuilder with a new class that adds these methods, if you want them.
3. A new wrapper class, ComponentHelper, has ComponentBuilder as a member. Then all these methods just access self.comp to do their work.

My gut feeling says 1, 3, and then 2, in that order. That is, it doesn't seem like a great sin to just put these right in ComponentBuilder. The whole idea there is to make life more convenient when using this builder-DSL, so the more convenience methods the better.