support aws s3 storage

[wintonzheng]

TODOs: [ ] add configurations so that you can configure s3 as the storage

For now, if you want to use s3:

1. set your AWS_ACCESS_KEY_ID, AWS_DEFAULT_REGION, and AWS_SECRET_ACCESS_KEY in your environment.
2. make sure you have two s3 buckets created under your aws account: skyvern-artifacts and skyvern-screenshots. If you want to use customized bucket names, make sure they're set for these two environment variables: AWS_S3_BUCKET_ARTIFACTS and AWS_S3_BUCKET_SCREENSHOTS
3. add StorageFactory.set_storage(S3Storage()) before https://github.com/Skyvern-AI/skyvern-cloud/blame/f9b7a50a9b83244d68226d27c0e8b5cd582bc763/skyvern/forge/app.py#L25

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:rocket:	This description was created by Ellipsis for commit e5f2ce180177b4b4c6d011dd3488814887b2399d

Summary:

This PR adds AWS S3 storage support to Skyvern, introducing the S3Storage class, configuration updates, and setup instructions.

Key points:

• Adds AWS S3 storage support to Skyvern.
• Introduces S3Storage class for S3 operations.
• Implements methods: build_uri, store_artifact, retrieve_artifact, get_share_link, get_share_links, store_artifact_from_path, save_streaming_file, get_streaming_file.
• Utilizes AsyncAWSClient for async S3 operations.
• Updates skyvern/config.py with SKYVERN_STORAGE_TYPE and S3 bucket settings.
• Modifies skyvern/forge/app.py to set storage to S3 if SKYVERN_STORAGE_TYPE is s3.
• Adds AWS_S3_BUCKET_ARTIFACTS and AWS_S3_BUCKET_SCREENSHOTS settings.
• Provides instructions for configuring S3 storage and setting environment variables.
• Updates documentation in docs/running-tasks/visualizing-results.mdx for S3 configuration.
• TODO: Add configurations for S3 as storage.
• Setup instructions for using S3 with environment variables and bucket names.

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