eDSL: no `cells` list when defining new component

[anshumanmohan]

As #2034 shows, it is possible to create a free-floating list of cells prior to the creation of a component, and to then associate those cells with a component when creating the component.

This is a little dicey and inelegant. This PR removes that power. You must now create a component, and then construct and insert cells specifically into that component.

This change has no victims in the existing codebase, since NTT (the only user of this feature) has stopped using it as of #2034.

If someone really wanted to, say, insert some "basic" cells into a variety of components and then add more stuff per component, like so:

def manifest_basic_cells_in_a_vacuum() -> list[Cell]:
  // elided
comp1 = prog.component("comp1", cells=manifest_basic_cells_in_a_vacuum())
comp2 = prog.component("comp2", cells=manifest_basic_cells_in_a_vacuum())
// add more cells to comp1 and comp2 as needed

They can still do that:

def add_basic_cells_to_comp(comp) -> ():
  // elided
comp1 = prog.component("comp1")
add_basic_cells_to_comp(comp1)
comp2 = prog.component("comp2")
add_basic_cells_to_comp(comp2)
// add more cells to comp1 and comp2 as needed

[rachitnigam]

Awesome! This also brings it in line with the interface of the Rust-based builder which only allows construction of cells on a particular component.

[anshumanmohan]

Super. I'll just leave this PR open in case @sampsyo, @EclecticGriffin, or @calebmkim know of a good reason to keep this feature around!

[EclecticGriffin]

No objections here!