Vendor dependencies

Let's see how I like this workflow.

vendor/cxx/tools/buck/prelude/python/interface.bzl

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+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under both the MIT license found in the
+# LICENSE-MIT file in the root directory of this source tree and the Apache
+# License, Version 2.0 found in the LICENSE-APACHE file in the root directory
+# of this source tree.
+
+# Input to build Python libraries and binaries (which are libraries wrapped in
+# an executable). The various functions here must returns the inputs annotated
+# below.
+PythonLibraryInterface = record(
+    # Shared libraries used by this Python library.
+    # {str.type: SharedLibraryInfo.type}
+    shared_libraries = field("function"),
+
+    # An iterator of PythonLibraryManifests objects. This is used to collect extensions.
+    # iterator of PythonLibraryManifests
+    iter_manifests = field("function"),
+
+    # A PythonLibraryManifestsInterface. This is used to convert manifests to
+    # arguments for pexing. Unlike iter_manifests this allows for more
+    # efficient calls, such as using t-sets projections.
+    # PythonLibraryManifestsInterface
+    manifests = field("function"),
+
+    # Returns whether this Python library includes hidden resources.
+    # bool
+    has_hidden_resources = field("function"),
+
+    # Converts the hidden resources in this Python library to arguments.
+    # _arglike of hidden resources
+    hidden_resources = field("function"),
+)
+
+PythonLibraryManifestsInterface = record(
+    # Returns the source manifests for this Python library.
+    # [_arglike] of source manifests
+    src_manifests = field("function"),
+
+    # Returns the files referenced by source manifests for this Python library.
+    # [_arglike] of source artifacts
+    src_artifacts = field("function"),
+
+    # Returns the source manifests for this Python library.
+    # [_arglike] of source manifests
+    src_type_manifests = field("function"),
+
+    # Returns the files referenced by source manifests for this Python library.
+    # [_arglike] of source artifacts
+    src_type_artifacts = field("function"),
+
+    # Returns the bytecode manifests for this Python library.
+    # [_arglike] of bytecode manifests
+    bytecode_manifests = field("function"),
+
+    # Returns the files referenced by bytecode manifests for this Python library.
+    # [_arglike] of bytecode artifacts
+    bytecode_artifacts = field("function"),
+
+    # Returns the resources manifests for this Python library.
+    # [_arglike] of resource manifests
+    resource_manifests = field("function"),
+
+    # Returns the files referenced by resource manifests for this Python library.
+    # [_arglike] of resource artifacts
+    resource_artifacts = field("function"),
+)