Collapse empty call expressions

[snady]

Use compact mode for call expressions if there are no parameters or line comments.

Running buildifier on

func(
)

doesn't format it because of ForceMultiline, but one could reasonably expect it to collapse into

func()

This comes up sometimes when removing attrs with buildozer -- if ForceMultiline=true but the rule/macro no longer has any attrs, the result will look like the first example e.g

some_macro(
  attr_to_remove=[
    ...
  ]
)

some_macro(
)