feat: add inpainting and outpainting samples and tests

[irataxy]

Description

Refactor generateImage.js to include parameters. Add all Imagen tests to a single test file.

Fixes b:367438781

Note: Before submitting a pull request, please open an issue for discussion if you are not associated with Google.

Checklist

• I have followed guidelines from CONTRIBUTING.MD and Samples Style Guide
• Tests pass: npm test (see Testing)
• Lint pass: npm run lint (see Style)
• These samples need a new API enabled in testing projects to pass (let us know which ones)
• These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• This pull request is from a branch created directly off of GoogleCloudPlatform/nodejs-docs-samples. Not a fork.
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• This sample adds a new sample directory, and I created GitHub Actions workflow for this sample
• This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample
• Please merge this PR for me once it is approved

[snippet-bot]

Here is the summary of changes.

You are about to add 5 region tags.

• ai-platform/snippets/imagen-edit-image-inpainting-insert-mask.js:20, tag generativeaionvertexai_imagen_edit_image_inpainting_insert_mask
• ai-platform/snippets/imagen-edit-image-inpainting-remove-mask.js:20, tag generativeaionvertexai_imagen_edit_image_inpainting_remove_mask
• ai-platform/snippets/imagen-edit-image-mask-free.js:20, tag generativeaionvertexai_imagen_edit_image_mask_free
• ai-platform/snippets/imagen-edit-image-outpainting-mask.js:20, tag generativeaionvertexai_imagen_edit_image_outpainting_mask
• ai-platform/snippets/imagen-generate-image.js:20, tag generativeaionvertexai_imagen_generate_image

You are about to delete 1 region tag.

• ai-platform/snippets/imagen/generateImage.js:20, tag generativeaionvertexai_imagen_generate_image

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[subfuzion]

Hi @irataxy This is a nice PR. I do have a couple of style suggestions for you, however. Thanks!

[subfuzion]

Hi @irataxy The updates look good, but unfortunately, tests are failing due to accelerator / machine type / location that you need to resolve.

[irataxy]

Hi @irataxy The updates look good, but unfortunately, tests are failing due to accelerator / machine type / location that you need to resolve.

Done. Those were unrelated tests.

[subfuzion]

@irataxy Sorry, I must have missed that this was set to auto-merge, but I didn't intend for this to get merged until I could talk to you about this issues I'm seeing with testing. It's not clear to me if these are related or not to your PR: https://github.com/GoogleCloudPlatform/nodejs-docs-samples/actions/runs/11219828098/job/31186647001?pr=3874#step:9:132