build: export matching patches (#41174)

* build: make patches/config.json an array of objects

This file was previously an object of patch_dir keys to repo values;
Now is an array of objects containing `patch_dir` and `repo` properties.
This makes other per-target properties (e.g. `grep`) possible.

* build: include Note metadata when exporting patches

* build: support keyword filtering in export_patches()

* build: add optional `--grep` arg to git-export-patches script

* build: update export_all_patches to understand new config file

* fixup! build: update export_all_patches to understand new config file

chore: make lint happy

* fixup! build: make patches/config.json an array of objects

chore: fix oops

* refactor: remove support for the old file format

There is more code using config.json than I thought, so the
effort-to-reward of supporting the old format is not worth it.

* build: update apply_all_patches to understand new config file

* build: update lint.js to understand new config file

* build: update patches-mtime-cache.py to understand new config file

* fixup! build: update apply_all_patches to understand new config file

fix: oops

* fixup! build: update apply_all_patches to understand new config file

fix minor syntax wart

* fixup! build: support keyword filtering in export_patches()

refactor: use idiomatic python

* refactor: warn if config.json has an invalid repo

script/patches-mtime-cache.py

@@ -12,7 +12,9 @@ from lib.patches import patch_from_dir
 
 
 def patched_file_paths(patches_config):
-    for patch_dir, repo in patches_config.items():
+    for target in patches_config:
+        patch_dir = target.get('patch_dir')
+        repo = target.get('repo')
         for line in patch_from_dir(patch_dir).split("\n"):
             if line.startswith("+++"):
                 yield posixpath.join(repo, line[6:])