Use bazel-gazelle instead of go/tools/gazelle everywhere (#1141)
* go_repository uses new Gazelle. @bazel_gazelle added to
go_rules_dependencies() until go_repository is moved to
@bazel_gazelle or removed.
* gazelle rule uses new Gazelle, but users should migrate to new
gazelle rule in @bazel_gazelle//:def.bzl.
* README.rst and Vendoring.md point to new Gazelle.
* wtool and tests/bazel_tests.bzl also updated. Data dependency
removed from build_with_old_sdk test (why was it there?).
* Old Gazelle left in place for now.
11 files changed
