Move diplomacy to standalone library absorbing aop

Splits out the aop and diplomacy modules into a standalone
library. Adds the new library as a dependency and updates the
in-tree diplomacy and aop modules to reference the new library with
deprecation warnings.

.gitmodules

@@ -7,3 +7,6 @@
 [submodule "dependencies/chisel"]
 	path = dependencies/chisel
 	url = https://github.com/chipsalliance/chisel.git
+[submodule "dependencies/diplomacy"]
+	path = dependencies/diplomacy
+	url = https://github.com/lordspacehog/diplomacy.git

.mill-version

@@ -0,0 +1 @@
+0.11.7

.scalafmt.conf

@@ -0,0 +1,32 @@
+version = 3.7.17
+runner.dialect = scala213
+
+maxColumn = 120
+align.preset = most
+continuationIndent.defnSite = 2
+assumeStandardLibraryStripMargin = true
+docstrings.style = SpaceAsterisk
+lineEndings = preserve
+includeCurlyBraceInSelectChains = false
+danglingParentheses.preset = true
+
+align.tokens."+" = [
+  {
+    code = ":"
+  }
+]
+
+newlines.beforeCurlyLambdaParams = never
+newlines.beforeMultiline = fold
+newlines.implicitParamListModifierForce = [before]
+
+verticalMultiline.atDefnSite = true
+
+optIn.annotationNewlines = true
+
+rewrite.rules = [SortImports, PreferCurlyFors, AvoidInfix]
+fileOverride {
+  "glob:**/common.sc/**" {
+     runner.dialect = scala3
+  }
+}

common.sc

@@ -1,8 +1,7 @@
 import mill._
 import mill.scalalib._
 
-trait HasChisel
-  extends ScalaModule {
+trait HasChisel extends ScalaModule {
   // Define these for building chisel from source
   def chiselModule: Option[ScalaModule]
 
@@ -21,20 +20,18 @@ trait HasChisel
 
   def chiselPluginIvy: Option[Dep]
 
-  override def scalacPluginIvyDeps: T[Agg[Dep]] = T(super.scalacPluginIvyDeps() ++ chiselPluginIvy.map(Agg(_)).getOrElse(Agg.empty[Dep]))
+  override def scalacPluginIvyDeps: T[Agg[Dep]] =
+    T(super.scalacPluginIvyDeps() ++ chiselPluginIvy.map(Agg(_)).getOrElse(Agg.empty[Dep]))
 }
 
-trait MacrosModule
-  extends ScalaModule {
+trait MacrosModule extends ScalaModule {
 
   def scalaReflectIvy: Dep
 
   override def ivyDeps = T(super.ivyDeps() ++ Some(scalaReflectIvy))
 }
 
-
-trait RocketChipModule
-  extends HasChisel {
+trait RocketChipModule extends HasChisel {
   override def mainClass = T(Some("freechips.rocketchip.diplomacy.Main"))
 
   def macrosModule: MacrosModule
@@ -45,16 +42,20 @@ trait RocketChipModule
   // should be cde/common.sc#CDEModule
   def cdeModule: ScalaModule
 
+  def diplomacyModule: ScalaModule
+
+  def diplomacyIvy: Option[Dep]
+
   def mainargsIvy: Dep
 
   def json4sJacksonIvy: Dep
 
-  override def moduleDeps = super.moduleDeps ++ Seq(macrosModule, hardfloatModule, cdeModule)
+  override def moduleDeps = super.moduleDeps ++ Seq(macrosModule, hardfloatModule, cdeModule, diplomacyModule)
 
   override def ivyDeps = T(
     super.ivyDeps() ++ Agg(
       mainargsIvy,
       json4sJacksonIvy
-    )
+    ) ++ diplomacyIvy
   )
 }

src/main/scala/aop/package.scala

@@ -0,0 +1,6 @@
+package freechips.rocketchip
+
+object aop {
+  @deprecated("aop has moved to the standalone diplomacy library.", "rocketchip 2.0.0")
+  val Select = _root_.org.chipsalliance.diplomacy.aop.Select
+}