Create sub-modifier and enum mechanism to replace -D modifiers

Spun off of history log from this comment:

>Rather than using -D modifiers, may be nice to be able to add sub-modifiers and enum for parameters or modifiers. Then for history, can have enum for the action parameter and sub-modifiers tied to different parameter enums. Is a bit extensive and invasive but I think it will be helpful for many other commands.
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>Happy to talk through design of this

_Originally posted by @isc-kiyer in https://github.com/intersystems/ipm/pull/578#discussion_r1815490761_

Edit 1/22/26:
This should capture a revamp of modifiers in general. One important part of this will be an "inversion of control" so that modules can define the commands, modifiers, and parameters they accept and IPM will provide hooks such that they can will work automatically, be auto-documented, and presented using the `help` command.

The idea behind -D modifiers is that we want to be able to pass through arguments and other configuration settings from general IPM commands to the specific module/resource processor that needs them, who can arbitrarily define them. One idea is that for every default parameter in module.xml, IPM will look for `IPM__` in the environment variables to see if something is set there. This means modules can insert their arbitrary