Set sensible OS platform attributes for scripts executed (macOS and Linux)

[dherder]

Problem

We need a way to differentiate between scripts specifically for macOS vs. Linux vs. both. Some bash scripts will execute on both OS platforms, but others will error because they are platform specific. The user should be able to set sensible defaults for which platforms they'd like to execute the script against when they are defining the script in gitops flows or when uploading in the UI.

Potential solutions

[noahtalerman]

@dherder thanks for tracking this. Agreed seeing "macOS & Linux" is confusing.