Updating positional-args check to be more comprehensive (#1393)

- Previous implementation just assumed that macros were called at the root of a BUILD file, and that all calls were to macros/rules except for explicit allowlist. Updating the check to more precisely validate whether something is a rule/macro, and checking all call expressions (including ones nested in dicts/attrs).
- Also updating IsMacro implementation to correctly support symblic macro definitions (`my_macro = macro(...)`)

Co-authored-by: Tim Malmström <oreflow@google.com>