## What does this PR do?
Passes environment variables to the `CloudRuntime` when loading an app from a file. Allows apps / works / flows to be properly configured when passing variables at runtime.
### Limitations
- Only implemented for the `CloudRuntime`
<details>
<summary><b>Before submitting</b></summary>
- Was this **discussed/agreed** via a GitHub issue? (not for typos and docs)
- [ ] Did you read the [contributor guideline](https://github.com/Lightning-AI/lightning/blob/master/.github/CONTRIBUTING.md), **Pull Request** section?
- [ ] Did you make sure your **PR does only one thing**, instead of bundling different changes together?
- Did you make sure to **update the documentation** with your changes? (if necessary)
- Did you write any **new necessary tests**? (not for typos and docs)
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</details>
## PR review
Anyone in the community is welcome to review the PR.
Before you start reviewing, make sure you have read the [review guidelines](https://github.com/Lightning-AI/lightning/wiki/Review-guidelines). In short, see the following bullet-list:
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<summary>Reviewer checklist</summary>
- [ ] Is this pull request ready for review? (if not, please submit in draft mode)
- [ ] Check that all items from **Before submitting** are resolved
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cc @borda
e57f12851f