add bulk alerts download collection runner with requires env vars

[tommynsong]

Description

Add a collection to do bulk alerts download as it is not yet available in the UI.

Motivation and Context

This change provide an alternative way to download alerts data in bulk since UI element is not available.

How Has This Been Tested?

This has been tested in the PC SA LAB

Screenshots (if appropriate)

Types of changes

New feature

• Bug fix (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 change)

Checklist

• [ x ] I have updated the documentation accordingly.
• [ x ] I have read the CONTRIBUTING document.
• [ x ] I have added tests to cover my changes if appropriate.
• [ x ] All new and existing tests passed.

[welcome-to-palo-alto-networks[bot]]

:tada: Thanks for opening this pull request! We really appreciate contributors like you! :raised_hands:

[welcome-to-palo-alto-networks[bot]]

:tada: Congrats on getting your first pull request merged! We here at Palo Alto Networks are so grateful! :heart: