feat(core): introduce nx import (#26847)

## Current Behavior
<!-- This is the behavior we have today -->

Importing other projects/ repositories into an Nx workspace is a natural
part of the Nx adoption story. However, there is no easy built in way of
handling this while maintaining `git` history.

## Expected Behavior
<!-- This is the behavior we should expect with the changes in this PR
-->

`nx import` is a new command which allows teams to merge code from other
repositories into a Nx workspace.

https://asciinema.org/a/oQiA9qOvA2z85AQvVJ5QRVTp1

## Related Issue(s)
<!-- Please link the issue being fixed so it gets closed when this is
merged. -->

Fixes #

e2e/nx/src/import.test.ts

@@ -0,0 +1,89 @@
+import {
+  checkFilesExist,
+  cleanupProject,
+  getSelectedPackageManager,
+  newProject,
+  runCLI,
+  updateJson,
+  updateFile,
+  e2eCwd,
+} from '@nx/e2e/utils';
+import { mkdirSync, rmdirSync } from 'fs';
+import { execSync } from 'node:child_process';
+import { join } from 'path';
+
+describe('Nx Import', () => {
+  let proj: string;
+  const tempImportE2ERoot = join(e2eCwd, 'nx-import');
+  beforeAll(() => {
+    proj = newProject({
+      packages: ['@nx/js'],
+      unsetProjectNameAndRootFormat: false,
+    });
+
+    if (getSelectedPackageManager() === 'pnpm') {
+      updateFile(
+        'pnpm-workspace.yaml',
+        `packages:
+  - 'projects/*'
+`
+      );
+    } else {
+      updateJson('package.json', (json) => {
+        json.workspaces = ['projects/*'];
+        return json;
+      });
+    }
+
+    try {
+      rmdirSync(join(tempImportE2ERoot));
+    } catch {}
+  });
+  afterAll(() => cleanupProject());
+
+  it('should be able to import a vite app', () => {
+    mkdirSync(join(tempImportE2ERoot), { recursive: true });
+    const tempViteProjectName = 'created-vite-app';
+    execSync(
+      `npx create-vite@latest ${tempViteProjectName} --template react-ts`,
+      {
+        cwd: tempImportE2ERoot,
+      }
+    );
+    const tempViteProjectPath = join(tempImportE2ERoot, tempViteProjectName);
+    execSync(`git init`, {
+      cwd: tempViteProjectPath,
+    });
+    execSync(`git add .`, {
+      cwd: tempViteProjectPath,
+    });
+    execSync(`git commit -am "initial commit"`, {
+      cwd: tempViteProjectPath,
+    });
+    execSync(`git checkout -b main`, {
+      cwd: tempViteProjectPath,
+    });
+
+    const remote = tempViteProjectPath;
+    const ref = 'main';
+    const source = '.';
+    const directory = 'projects/vite-app';
+
+    runCLI(
+      `import ${remote} ${directory} --ref ${ref} --source ${source} --no-interactive`,
+      {
+        verbose: true,
+      }
+    );
+
+    checkFilesExist(
+      'projects/vite-app/.gitignore',
+      'projects/vite-app/package.json',
+      'projects/vite-app/index.html',
+      'projects/vite-app/vite.config.ts',
+      'projects/vite-app/src/main.tsx',
+      'projects/vite-app/src/App.tsx'
+    );
+    runCLI(`vite:build created-vite-app`);
+  });
+});

packages/nx/src/command-line/import/command-object.ts

@@ -0,0 +1,48 @@
+import { CommandModule } from 'yargs';
+import { linkToNxDevAndExamples } from '../yargs-utils/documentation';
+import { withVerbose } from '../yargs-utils/shared-options';
+import { handleErrors } from '../../utils/params';
+
+export const yargsImportCommand: CommandModule = {
+  command: 'import [sourceRemoteUrl] [destination]',
+  describe: false,
+  builder: (yargs) =>
+    linkToNxDevAndExamples(
+      withVerbose(
+        yargs
+          .positional('sourceRemoteUrl', {
+            type: 'string',
+            description: 'The remote URL of the source to import',
+          })
+          .positional('destination', {
+            type: 'string',
+            description:
+              'The directory in the current workspace to import into',
+          })
+          .option('source', {
+            type: 'string',
+            description:
+              'The directory in the source repository to import from',
+          })
+          .option('ref', {
+            type: 'string',
+            description: 'The branch from the source repository to import',
+          })
+          .option('interactive', {
+            type: 'boolean',
+            description: 'Interactive mode',
+            default: true,
+          })
+      ),
+      'import'
+    ),
+  handler: async (args) => {
+    const exitCode = await handleErrors(
+      (args.verbose as boolean) ?? process.env.NX_VERBOSE_LOGGING === 'true',
+      async () => {
+        return (await import('./import')).importHandler(args as any);
+      }
+    );
+    process.exit(exitCode);
+  },
+};