Add DynamicGroup for runtime-defined option groups

[uenoku]

Introduces a new DynamicGroup class that allows option groups and cases
to be defined with runtime parameters instead of requiring compile-time
singleton objects.

This enables more flexible option group definitions, particularly useful
for programmatically generated hardware where option groups cannot be
defined as static objects.

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Type of Improvement

• Feature (or new API)

Desired Merge Strategy

• Squash: The PR will be squashed and merged (choose this if you have no preference).

Release Notes

Introduces a new DynamicGroup class that allows option groups
to be defined with runtime parameters instead

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[seldridge]

High-level: is there a way to do this which doesn't make everything string-based?

[seldridge]

Nit: this is fine to include up top.

[seldridge]

I don't love it due to the complexity, but this should probably implement the val naming with a suggestName method like other things in Chisel.

[uenoku]

I think I want to disallow that level of dynamic behavior. The group name is essentially user/designer facing API even when they are generated dynamically.

[uenoku]

High-level: is there a way to do this which doesn't make everything string-based?

I can provide following level of trait based interface, though I didn't like it because of the amount of boilerplate.

trait PlatformType {
  def FPGA: Case
  def ASIC: Case
}
val platform = DynamicGroup[PlatformType]("Platform", Seq("FPGA", "ASIC")) { group =>
  new PlatformType {
    def FPGA = group("FPGA")
    def ASIC = group("ASIC")
  }
}
platform.FPGA

Ideally I wanted to do following but I thought scala3 reflection would be necessary to do this.

trait PlatformType {
  def FPGA: Case
  def ASIC: Case
}
val platform = DynamicGroup[PlatformType]("Platform")
platform.FPGA

[jackkoenig]

We could make this work:

trait PlatformType extends DynamicGroup {
  object FPGA extends Case
  object ASIC extends Case
}
val platform = DynamicGroup[PlatformType]("Platform")
// or
val Platform = DynamicGroup(new PlatformType {})

Or something like that without Scala reflection

[uenoku]

62ae69d implements trait based API that uses macro. I disclose that I needed quite a bit help from AI for writing DynamicGroupIntf.scala and it might be sloppy, so it might be better to start with a previous commit that's much more simpler. Though I believe that macro correctly implements API we generally want.