fix(aws-cdk): correct project-name argument mapping in cdk init

[TORIFUKUKaiou]

The --project-name (-n) option for cdk init was silently ignored because the legacy code path in cli.ts referenced args.name (a non-existent property) instead of args.projectName.

Yargs automatically converts the kebab-case option --project-name to args.projectName via camelCase conversion, but the mapping incorrectly used args.name, causing the value to always be undefined and falling back to the directory name.

Also fixes the test description that incorrectly referred to the option as --name instead of --project-name.

Fixes aws/aws-cdk#31992

Validation

I verified the fix locally in the devcontainer environment by running the modified CLI and comparing the outputs.

1. Verify yargs argument parsing:
   Added a new unit test in packages/aws-cdk/test/cli/cli-arguments.test.ts to verify that the --project-name option correctly maps to the projectName property in the config.

2. Verify generated project structure and files:
   I generated two projects with the same target project name (awesome-app)—one by relying on the default fallback (directory name) and the other by explicitly specifying --project-name:

   # 1. Project without --project-name (inheriting directory name)
   mkdir /tmp/awesome-app && cd /tmp/awesome-app
   node /workspace/aws-cdk-cli/packages/aws-cdk/bin/cdk init app --language typescript --generate-only
   
   # 2. Project with --project-name in a different directory
   mkdir /tmp/cdk-verify-test && cd /tmp/cdk-verify-test
   node /workspace/aws-cdk-cli/packages/aws-cdk/bin/cdk init app --language typescript --project-name awesome-app --generate-only
   
   # 3. Compare the two generated projects
   diff -r /tmp/awesome-app /tmp/cdk-verify-test

   Result:
   The diff command yielded no differences, confirming that --project-name awesome-app was correctly respected and generated identical files (including package.json, stack file names, and class names inside lib/ and bin/) regardless of the directory name.

Checklist

• This change contains a major version upgrade for a dependency and I confirm all breaking changes are addressed
  • Release notes for the new version:

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

[sai-ray]

Hey @TORIFUKUKaiou, nice catch and thanks for fixing this! It's been silently doing nothing since it was added, the handler was reading the wrong property, so it always fell back to the folder name.

One thing: we'll need a test that actually runs the command with option and confirms the name comes through, so this can't quietly break again.

[sai-ray]

Could you also update your branch with the latest main before we run CI? It's a bit behind, and I'd like CI to run against the current base. Thanks!