escape.d: deduplicate arg/param iteration logic

[dkorpel]

Reduces indentation, so best reviewed with whitespace off

[dlang-bot]

Thanks for your pull request and interest in making D better, @dkorpel! We are looking forward to reviewing it, and you should be hearing from a maintainer soon. Please verify that your PR follows this checklist:

• My PR is fully covered with tests (you can see the coverage diff by visiting the details link of the codecov check)
• My PR is as minimal as possible (smaller, focused PRs are easier to review than big ones)
• I have provided a detailed rationale explaining my changes
• New or modified functions have Ddoc comments (with Params: and Returns:)

Please see CONTRIBUTING.md for more information.

---

If you have addressed all reviews or aren't sure how to proceed, don't hesitate to ping us with a simple comment.

Bugzilla references

Your PR doesn't reference any Bugzilla issue.

If your PR contains non-trivial changes, please reference a Bugzilla issue or create a manual changelog.

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + dmd#15202"

[dkorpel]

core.exception.ArrayIndexError@D:\a\1\s\compiler\src\dmd\root\array.d(131): index [172292160] is out of bounds for array of length 94532592

Yikes

[RazvanN7]

@dkorpel rebase this and let's get it in.

[dkorpel]

The failure on OMF is persistent

[dkorpel]

The failure on OMF is persistent

Well guess what's gone now :slightly_smiling_face:

But it has merge conflicts and want to refactor this a different way now, so I'll open a new PR for that.