[Test Owners] Add script to get owners for files (#193277)

## Summary

Node script to report ownership of a given file in our repo.

The script's source of truth is `.github/CODEOWNERS`, which is generated
by `@kbn/generate`

In order to reach the goal of have zero files without code ownership,
this is one small step along the way.

### To Test

#### Happy Path
`node scripts/get_owners_for_file.js --file
packages/kbn-ace/src/ace/modes/index.ts`
```
 succ elastic/kibana-management
```

#### Unknown Path
`node scripts/get_owners_for_file.js --file some-file.txt`
```
ERROR Ownership of file [some-file.txt] is UNKNOWN
```

#### Error Path
`node scripts/get_owners_for_file.js`
```
ERROR Missing --flag argument

  node scripts/get_owners_for_file.js

  Report file ownership from GitHub CODEOWNERS file.

  Options:
    --file             Required, path to the file to report owners for.
    --verbose, -v      Log verbosely
    --debug            Log debug messages (less than verbose)
    --quiet            Only log errors
    --silent           Don't log anything
    --help             Show this message
```

### Notes

Along with this small pr, next will be to ensure owners are assigned to
all ES and KBN Archives. See more info in the link below:

Contributes to: #192979

---------

Co-authored-by: kibanamachine <[email protected]>

packages/kbn-code-owners/index.ts

@@ -8,4 +8,8 @@
  */
 
 export type { PathWithOwners } from './src/file_code_owner';
-export { getPathsWithOwnersReversed, getCodeOwnersForFile } from './src/file_code_owner';
+export {
+  getPathsWithOwnersReversed,
+  getCodeOwnersForFile,
+  runGetOwnersForFileCli,
+} from './src/file_code_owner';

packages/kbn-code-owners/src/file_code_owner.ts

@@ -8,9 +8,10 @@
  */
 
 import { REPO_ROOT } from '@kbn/repo-info';
-import { createFailError } from '@kbn/dev-cli-errors';
+import { createFailError, createFlagError } from '@kbn/dev-cli-errors';
 import { join as joinPath } from 'path';
 import { existsSync, readFileSync } from 'fs';
+import { run } from '@kbn/dev-cli-runner';
 
 import type { Ignore } from 'ignore';
 import ignore from 'ignore';
@@ -20,6 +21,10 @@ export interface PathWithOwners {
   teams: string;
   ignorePattern: Ignore;
 }
+const existOrThrow = (targetFile: string) => {
+  if (existsSync(targetFile) === false)
+    throw createFailError(`Unable to determine code owners: file ${targetFile} Not Found`);
+};
 
 /**
  * Get the .github/CODEOWNERS entries, prepared for path matching.
@@ -29,9 +34,7 @@ export interface PathWithOwners {
  */
 export function getPathsWithOwnersReversed(): PathWithOwners[] {
   const codeownersPath = joinPath(REPO_ROOT, '.github', 'CODEOWNERS');
-  if (existsSync(codeownersPath) === false) {
-    throw createFailError(`Unable to determine code owners: file ${codeownersPath} not found`);
-  }
+  existOrThrow(codeownersPath);
   const codeownersContent = readFileSync(codeownersPath, { encoding: 'utf8', flag: 'r' });
   const codeownersLines = codeownersContent.split(/\r?\n/);
   const codeowners = codeownersLines
@@ -66,3 +69,32 @@ export function getCodeOwnersForFile(
 
   return match?.teams;
 }
+
+/**
+ * Run the getCodeOwnersForFile() method above.
+ * Report back to the cli with either success and the owner(s), or a failure.
+ *
+ * This function depends on a --file param being passed on the cli, like this:
+ * $ node scripts/get_owners_for_file.js --file SOME-FILE
+ */
+export async function runGetOwnersForFileCli() {
+  run(
+    async ({ flags, log }) => {
+      const targetFile = flags.file as string;
+      if (!targetFile) throw createFlagError(`Missing --flag argument`);
+      existOrThrow(targetFile); // This call is duplicated in getPathsWithOwnersReversed(), so this is a short circuit
+      const result = getCodeOwnersForFile(targetFile);
+      if (result) log.success(result);
+      else log.error(`Ownership of file [${targetFile}] is UNKNOWN`);
+    },
+    {
+      description: 'Report file ownership from GitHub CODEOWNERS file.',
+      flags: {
+        string: ['file'],
+        help: `
+      --file             Required, path to the file to report owners for.
+              `,
+      },
+    }
+  );
+}

packages/kbn-code-owners/tsconfig.json

@@ -15,6 +15,7 @@
   ],
   "kbn_references": [
     "@kbn/repo-info",
-    "@kbn/dev-cli-errors"
+    "@kbn/dev-cli-errors",
+    "@kbn/dev-cli-runner"
   ]
 }

scripts/get_owners_for_file.js

@@ -0,0 +1,11 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+require('../src/setup_node_env');
+require('@kbn/code-owners').runGetOwnersForFileCli();