[FIRRTL] Add GCT Data/Mem Tap Prefixing to PrefixModules

[seldridge]

Change PrefixModules to rename external modules that are Grand Central
data or memory taps. This is done to align the behavior of CIRCT with
the Scala FIRRTL Compiler.

Fixes #2027.

[prithayan]

Looks good.
I think next we need to update extern modules in NLAs too.

[seldridge]

I tried this with the test case you added for NLAs. The actual logic should be fine, but the rename of external modules needs to clone modules if there are multiple prefixes. I erroneously thought that the prefixes array was "all the prefixes that need to be applied" instead of a list of different prefixes which require duplicating the module. I'll update this and ask for re-review.

[seldridge]

I fixed this to actually do the right thing (clone the external module if there are multiple prefixes). I would be surprised if any Grand Central code exercises this, but we'll future proof what we're doing here. This copies the behavior for how normal, non-external modules are duplicated if they have multiple prefixes.

I don't think there is any update needed for this to work with NLAs. All the NLA handling logic happens in either runOnOperation or in renameModuleBody. This PR only modified renameModuleBody to stop excluding external modules from renaming, so any NLA updates are then picked up by renameModuleBody and things appear to just work. Or: modifying the test case you added, @prithayan, to have NLAs target a GCT data tap seems to "just work":

firrtl.circuit "NLATop" {
  firrtl.nla @nla [@NLATop, @Aardvark, @Zebra] ["test", "test", "Zebra"]
  firrtl.nla @nla_1 [@NLATop, @Aardvark, @Zebra] ["test", "test_1", "Zebra"]
  firrtl.module @NLATop()
    attributes {annotations = [{
      class = "sifive.enterprise.firrtl.NestedPrefixModulesAnnotation",
      prefix = "T_",
      inclusive = true
    }]} {
    firrtl.instance test  {annotations = [{circt.nonlocal = @nla, class = "circt.nonlocal"}, {circt.nonlocal = @nla_1, class = "circt.nonlocal"} ]}@Aardvark()
    firrtl.instance test2 @Zebra()
  }
  firrtl.module @Aardvark()
    attributes {annotations = [{
      class = "sifive.enterprise.firrtl.NestedPrefixModulesAnnotation",
      prefix = "A_",
      inclusive = false
    }]} {
    firrtl.instance test {annotations = [{circt.nonlocal = @nla, class = "circt.nonlocal"}]}@Zebra()
    firrtl.instance test1 {annotations = [{circt.nonlocal = @nla_1, class = "circt.nonlocal"}]}@Zebra()
  }
  firrtl.extmodule @Zebra()
    attributes {annotations = [{
      class = "sifive.enterprise.grandcentral.DataTapsAnnotation"}],
      defname = "DataTap"}
}

Produces:

module  {
  firrtl.circuit "T_NLATop"   {
    firrtl.nla @nla [@T_NLATop, @T_Aardvark, @T_A_Zebra] ["test", "test", "Zebra"]
    firrtl.nla @nla_1 [@T_NLATop, @T_Aardvark, @T_A_Zebra] ["test", "test_1", "Zebra"]
    firrtl.module @T_NLATop() {
      firrtl.instance test  {annotations = [{circt.nonlocal = @nla, class = "circt.nonlocal"}, {circt.nonlocal = @nla_1, class = "circt.nonlocal"}]} @T_Aardvark()
      firrtl.instance test2  @T_Zebra()
    }
    firrtl.module @T_Aardvark() {
      firrtl.instance test  {annotations = [{circt.nonlocal = @nla, class = "circt.nonlocal"}]} @T_A_Zebra()
      firrtl.instance test1  {annotations = [{circt.nonlocal = @nla_1, class = "circt.nonlocal"}]} @T_A_Zebra()
    }
    firrtl.extmodule @T_Zebra() attributes {annotations = [{class = "sifive.enterprise.grandcentral.DataTapsAnnotation"}], defname = "T_DataTap"}
    firrtl.extmodule @T_A_Zebra() attributes {annotations = [{class = "sifive.enterprise.grandcentral.DataTapsAnnotation"}], defname = "T_A_DataTap"}
  }
}