Give option to keep CSV files locally and skip upload to S3

[mpcarter]

Problem

When testing pipelines on a local machine, you don't always need to actually send the files to S3. Sometimes you just want to
verify the data is written correctly to CSV file.

Proposed changes

With this change, specifying the s3_bucket value as 'localhost' will skip the upload to S3 and not remove the files from temp_dir.

It also skips creation of AWS session, avoiding need to have AWS credentials for local testing.

Types of changes

What types of changes does your code introduce to PipelineWise?
Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Checklist

• Description above provides context of the change
• I have added tests that prove my fix is effective or that my feature works
• Unit tests for changes (not needed for documentation changes)
• CI checks pass with my changes
• Bumping version in setup.py is an individual PR and not mixed with feature or bugfix PRs
• Commit message/PR title starts with [AP-NNNN] (if applicable. AP-NNNN = JIRA ID)
• Branch name starts with AP-NNN (if applicable. AP-NNN = JIRA ID)
• Commits follow "How to write a good git commit message"
• Relevant documentation is updated including usage instructions

[Samira-El]

hey @mpcarter, it's been a while since this PR has been created 😅 !
I think it's a good idea, if you're still interested in this, would you mind making CI checks pass?