fix(cli-lib): cannot bootstrap specific environment (#31713)

### Issue

Closes #31656

### Reason for this change

When boostrapping, users may need to explicitly provide the environment if it can be determined from the app or shell environment. Previously this was not possible using the cli-lib-alpha package.

### Description of changes

Add a new argument to support environments.

### Description of how you validated changes

Unit test case was added.

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: mrgrain

Diff for: packages/@aws-cdk/cli-lib-alpha/lib/cli.ts

@@ -172,7 +172,9 @@ export class AwsCdkCli implements IAwsCdkCli {
    * cdk bootstrap
    */
   public async bootstrap(options: BootstrapOptions = {}) {
+    const envs = options.environments ?? [];
     const bootstrapCommandArgs: string[] = [
+      ...envs,
       ...renderBooleanArg('force', options.force),
       ...renderBooleanArg('show-template', options.showTemplate),
       ...renderBooleanArg('terminationProtection', options.terminationProtection),

Diff for: packages/@aws-cdk/cli-lib-alpha/lib/commands/bootstrap.ts

@@ -4,6 +4,14 @@ import { SharedOptions } from './common';
  * Options to use with cdk bootstrap
  */
 export interface BootstrapOptions extends SharedOptions {
+  /**
+   * The target AWS environments to deploy the bootstrap stack to.
+   * Uses the following format: `aws://<account-id>/<region>`
+   *
+   * @example "aws://123456789012/us-east-1"
+   * @default - Bootstrap all environments referenced in the CDK app or determine an environment from local configuration.
+   */
+  readonly environments?: string[];
 
   /**
    * The name of the CDK toolkit stack to create

Diff for: packages/@aws-cdk/cli-lib-alpha/test/commands.test.ts

@@ -369,4 +369,16 @@ describe('list', () => {
     );
   });
 
+  test('bootstrap specific environment', async () => {
+    // WHEN
+    await cdk.bootstrap({
+      environments: ['aws://123456789012/us-east-1'],
+    });
+
+    // THEN
+    expect(jest.mocked(cli.exec)).toHaveBeenCalledWith(
+      ['bootstrap', 'aws://123456789012/us-east-1', '--all'],
+      expect.anything(),
+    );
+  });
 });