Replace most uses of macros.bzl with skia_rules.bzl or flags.bzl

//bazel/macros.bzl is a convenient place for symbols, but adds an
implicit dependency on our go and python toolchain. The vast majority
of our files do not need this and this causes external clients
to need to install many extra things in their WORKSPACE file.

Using skia_rules.bzl and flags.bzl should allow //:skia_public
to be built with no external dependencies (other than
bazel_skylib, which most projects use anyway [citation needed]).

See also http://cl/516303424

Change-Id: I7ecb94e97514c7147dcddf96840e662c8e3fad66
Bug: skia:14114
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/655856
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
197 files changed