third_party: slurp in edk2, kubernetes, mkfs.xfs

This finishes the move from core/build/* into third_party/.

While at first this might look like wasted bandwidth, this separation
will make much more sense in the future, where different parts (not only
the Smalltown core) might depend on shared external dependencies. In
addition, having everything in third_party laid out in a similar fashion
lends itself to writing more general rules. Already there is quite a bit
of deduplicaiton that we could remove for reliability and readability.

This does not fix the problem of the big honkin' genrule for mkfs.xfs -
while I think we should fix it sooner than later by building a real
toolchain, that time is not yet now. But at least we've moved things out
of the way so that we can then drop in a better mkfs.xfs, once it is
built so.

Test Plan: build file mangling, CI should cover this

X-Origin-Diff: phab/D391
GitOrigin-RevId: fb99c6a6270c5c6a56eeb4f18a41323ffebbc655
diff --git a/third_party/util-linux/BUILD.bazel b/third_party/util-linux/BUILD.bazel
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/third_party/util-linux/BUILD.bazel
diff --git a/third_party/util-linux/external.bzl b/third_party/util-linux/external.bzl
new file mode 100644
index 0000000..84b17ec
--- /dev/null
+++ b/third_party/util-linux/external.bzl
@@ -0,0 +1,32 @@
+#  Copyright 2020 The Monogon Project Authors.
+#
+#  SPDX-License-Identifier: Apache-2.0
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
+def util_linux_external(name, version):
+    sums = {
+        "2.34": "1d0c1a38f8c14a2c251681907203cccc78704f5702f2ef4b438bed08344242f7"
+    }
+    all_content = """filegroup(name = "all", srcs = glob(["**"]), visibility = ["//visibility:public"])"""
+
+    http_archive(
+        name = name,
+        build_file_content = all_content,
+        sha256 = sums[version],
+        strip_prefix = "util-linux-" + version,
+        urls = ["https://git.kernel.org/pub/scm/utils/util-linux/util-linux.git/snapshot/util-linux-%s.tar.gz" % version],
+    )
+