Fix Arg.name and earlyLocalName for probes (backport #4359)

[mergify]

Contributor Checklist

• Did you add Scaladoc to every public function/method?
• Did you add at least one test demonstrating the PR?
• Did you delete any extraneous printlns/debugging code?
• Did you specify the type of improvement?
• Did you add appropriate documentation in docs/src?
• Did you request a desired merge strategy?
• Did you add text to be included in the Release Notes for this change?

Type of Improvement

• Bugfix

Names for probe Args will be the default toString. For example, if you use DataMirror to get the earlyName of a probe (derived from Arg.name), you will see this default toString.

import chisel3._
import chisel3.probe._
import chisel3.reflect.DataMirror
import chisel3.util.experimental.BoringUtils
import circt.stage.ChiselStage

class ProbedClockedData[D <: Data](gen: => D) extends Bundle {
  val dataProbe = Probe(gen)
  def data      = probe.read(dataProbe)

  val clockProbe = Probe(Clock())
  def clock      = probe.read(clockProbe)

  val resetProbe = Probe(Reset())
  def reset      = probe.read(resetProbe)

  def tapAndConnect(ref: D, clock: Clock, reset: Reset) = {
    dataProbe  := BoringUtils.tap(ref)
    clockProbe := BoringUtils.tap(clock)
    resetProbe := BoringUtils.tap(reset)
  }
}

class Dut extends Module {
  val io = IO(new Bundle {
    val in  = Input(UInt(4.W))
    val out = Output(UInt(4.W))
  })
}

class TestHarness extends Module {
  val dut    = Module(new Dut)
  val probed = Wire(new ProbedClockedData(chiselTypeOf(dut.io)))
  probed.tapAndConnect(dut.io, dut.clock, dut.reset)

  println(s"probed.data name: ${DataMirror.queryNameGuess(probed.data)}")
}

object Main extends App {
  println(ChiselStage.emitCHIRRTL(gen = new TestHarness))
}

probed.data name: Node(TestHarness.probed.dataProbe: Wire[AnonymousBundle])

If that name is ever used for an identifier, Chisel will throw an exception due to the invalid name.

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Release Notes

Reviewer Checklist (only modified by reviewer)

• Did you add the appropriate labels? (Select the most appropriate one based on the "Type of Improvement")
• Did you mark the proper milestone (Bug fix: 3.6.x, 5.x, or 6.x depending on impact, API modification or big change: 7.0)?
• Did you review?
• Did you check whether all relevant Contributor checkboxes have been checked?
• Did you do one of the following when ready to merge:
  • Squash: You/ the contributor Enable auto-merge (squash), clean up the commit message, and label with Please Merge.
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---

This is an automatic backport of pull request #4359 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 15c3cc9 has failed:

On branch mergify/bp/6.x/pr-4359
Your branch is up to date with 'origin/6.x'.

You are currently cherry-picking commit 15c3cc921.
  (fix conflicts and run "git cherry-pick --continue")
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  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   core/src/main/scala/chisel3/internal/firrtl/IR.scala

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   src/test/scala/chiselTests/ProbeSpec.scala

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally