Update diff counts capsule parameter UI

[phoman14]

Changes

Updates the Code Ocean app panel parameter UI for the diff counts capsule.

• update count_type to list with raw, clean, filt options (default: filt).
• move count_type to first position in Basic category.
• use list controls for differential parameters.
• order diff normalization options.
• clarify diff normalization methods.

Issues

No linked issue.

PR Checklist

(Strikethrough any points that are not applicable.)

• This comment contains a description of changes with justifications, with any relevant issues linked.
• Run the capsule in Code Ocean and ensure it completes successfully with no errors.
• Update CHANGELOG.md with a short description of any user-facing changes and reference the PR number. Follow the style described in https://style.tidyverse.org/news.html
• The tests workflow succeeds on the latest commit.