refactor(builtin): renamed npm_package to pkg_npm to match naming convention

It also frees up the name `npm_package` which may be useful in the future as a non-packaging representation of an npm package as an alternative to promoting js_library to the public API.

BREAKING CHANGE:
`npm_package` renamed to `pkg_npm`. This is to match the naming convention for package rules https://docs.bazel.build/versions/master/be/pkg.html.

packages/create/BUILD.bazel

diff --git a/packages/create/BUILD.bazel b/packages/create/BUILD.bazel
index c0d126c..8c2d60c 100644
--- a/packages/create/BUILD.bazel
+++ b/packages/create/BUILD.bazel
@@ -1,4 +1,4 @@
-load("@build_bazel_rules_nodejs//:tools/defaults.bzl", "nodejs_test", "npm_package")
+load("@build_bazel_rules_nodejs//:tools/defaults.bzl", "nodejs_test", "pkg_npm")
 load("//third_party/github.com/bazelbuild/bazel-skylib:rules/copy_file.bzl", "copy_file")
 
 # Copy common bazelrc file to be included in this package
@@ -8,7 +8,7 @@
     out = "common.bazelrc",
 )
 
-npm_package(
+pkg_npm(
     name = "npm_package",
     srcs = [
         "README.md",