hack: add a script to reformat the imports

add a helper script which reads the sort ordering expectation
from our .golangci.yml (source of truth) and automatically
constructs the recommended command line to run to conform.

Also add Makefile targets to make the usage trivial:
```
$ make sort-imports
```

Depends on python3 and gci: https://github.com/daixiang0/gci

Signed-off-by: Francesco Romani <[email protected]>

Author: ffromani

Makefile

@@ -148,6 +148,18 @@ test-upgrade-e2e: build-e2e-all
 test-must-gather-e2e: build-must-gather-e2e
 	hack/run-test-must-gather-e2e.sh
 
+# intentional left out:
+#   api/, because autogeneration
+#   cmd/, because kubebuilder scaffolding
+.PHONY:
+sort-imports:
+	@hack/sort-imports.py -v ./test/
+	@hack/sort-imports.py -v ./internal/
+	@hack/sort-imports.py -v ./pkg/
+	@hack/sort-imports.py -v ./rte/
+	@hack/sort-imports.py -v ./tools/
+	@hack/sort-imports.py -v ./nrovalidate/
+
 .PHONY: lint
 lint: update-buildinfo golangci-lint ## Run golangci-lint linter
 	$(GOLANGCI_LINT) --verbose run --print-resources-usage --exclude-dirs test/internal/k8simported

hack/sort-imports.py

@@ -0,0 +1,45 @@
+#!/usr/bin/env python
+
+import argparse
+import os
+import subprocess
+import sys
+import yaml
+
+
+def make_gci_commandline(tree, ciconfig=".golangci.yml"):
+    with open(ciconfig) as src:
+        cfg = yaml.safe_load(src)
+    try:
+        sections = cfg['linters-settings']['gci']['sections']
+    except KeyError:
+        sys.stderr.write("cannot find gci configuration on %s\n" % ciconfig)
+        sys.exit(2)
+    cmdline = [
+        "gci", "write", "--custom-order",
+    ]
+    for sect in sections:
+        cmdline.extend(("-s", sect))
+    cmdline.append(tree)
+    return cmdline
+
+
+def _main(args):
+    cmdline = make_gci_commandline(args.tree)
+    if args.verbose and not args.dry_run:
+        sys.stderr.write("running: [%s]\n" % " ".join(cmdline))
+    if args.dry_run:
+        print(" ".join(cmdline))
+        return
+    subprocess.run(cmdline)
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(
+        prog='sort-imports.py',
+        description='sort golang imports according to project standards delegating to gci')
+    parser.add_argument('tree')
+    parser.add_argument('-v', '--verbose', action='store_true')
+    parser.add_argument('-D', '--dry-run', action='store_true')
+    args = parser.parse_args()
+    _main(args)