[WIP] feat: Personal applicataion of custom modifiers

[lorenzennio]

Description

This is my personal use of a custom modifier. It includes some additional features:

• usage of custom function
• setting of custom parameter type
• output of custom function does not have to match total number of bins (rather it places in the mask)

Checklist Before Requesting Reviewer

• Tests are passing
• "WIP" removed from the title of the pull request
• Selected an Assignee for the PR to be responsible for the log summary

Before Merging

For the PR Assignees:

• Summarize commit messages into a comprehensive review of the PR

[matthewfeickert]

@lorenzennio can you rebase this to drop everything except for the relevant commit (the "personal use case of custom modifier" one) so that branch diff is more useful?