feat(dev-infra): create tool to determine conflicts created by a PR (#37051)

Creates a tool in ng-dev to determine the PRs which become conflicted
by merging a specified PR.  Often the question is brought up of how
many PRs require a rebase as a result of a change.  This script allows
to determine this impact.

PR Close #37051

dev-infra/utils/github.ts

@@ -0,0 +1,91 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {graphql as unauthenticatedGraphql} from '@octokit/graphql';
+
+import {params, query as graphqlQuery, types} from 'typed-graphqlify';
+import {NgDevConfig} from './config';
+
+/** The configuration required for github interactions. */
+type GithubConfig = NgDevConfig['github'];
+
+/**
+ * Authenticated instance of Github GraphQl API service, relies on a
+ * personal access token being available in the TOKEN environment variable.
+ */
+const graphql = unauthenticatedGraphql.defaults({
+  headers: {
+    // TODO(josephperrott): Remove reference to TOKEN environment variable as part of larger
+    // effort to migrate to expecting tokens via GITHUB_ACCESS_TOKEN environment variables.
+    authorization: `token ${process.env.TOKEN || process.env.GITHUB_ACCESS_TOKEN}`,
+  }
+});
+
+/** Get all pending PRs from github  */
+export async function getPendingPrs<PrSchema>(prSchema: PrSchema, {owner, name}: GithubConfig) {
+  // The GraphQL query object to get a page of pending PRs
+  const PRS_QUERY = params(
+      {
+        $first: 'Int',      // How many entries to get with each request
+        $after: 'String',   // The cursor to start the page at
+        $owner: 'String!',  // The organization to query for
+        $name: 'String!',   // The repository to query for
+      },
+      {
+        repository: params({owner: '$owner', name: '$name'}, {
+          pullRequests: params(
+              {
+                first: '$first',
+                after: '$after',
+                states: `OPEN`,
+              },
+              {
+                nodes: [prSchema],
+                pageInfo: {
+                  hasNextPage: types.boolean,
+                  endCursor: types.string,
+                },
+              }),
+        })
+      });
+  const query = graphqlQuery('members', PRS_QUERY);
+
+  /**
+   * Gets the query and queryParams for a specific page of entries.
+   */
+  const queryBuilder = (count: number, cursor?: string) => {
+    return {
+      query,
+      params: {
+        after: cursor || null,
+        first: count,
+        owner,
+        name,
+      },
+    };
+  };
+
+  // The current cursor
+  let cursor: string|undefined;
+  // If an additional page of members is expected
+  let hasNextPage = true;
+  // Array of pending PRs
+  const prs: Array<PrSchema> = [];
+
+  // For each page of the response, get the page and add it to the
+  // list of PRs
+  while (hasNextPage) {
+    const {query, params} = queryBuilder(100, cursor);
+    const results = await graphql(query, params) as typeof PRS_QUERY;
+
+    prs.push(...results.repository.pullRequests.nodes);
+    hasNextPage = results.repository.pullRequests.pageInfo.hasNextPage;
+    cursor = results.repository.pullRequests.pageInfo.endCursor;
+  }
+  return prs;
+}