IJPL-165684 Dispose a default project session on a connection disposal as well

(cherry picked from commit 362288bbb80ca5c5f4c5b33efd2faf746fc45168)

IJ-CR-148844

GitOrigin-RevId: c014e19388e567f3c74393219ad63484e40005c3

platform/rd-platform-community/api-dump.txt

@@ -1,4 +1,5 @@
 f:com.intellij.openapi.rd.LifetimeDisposableExKt
+- sf:attachAsChildTo(com.intellij.openapi.Disposable,com.jetbrains.rd.util.lifetime.Lifetime):V
 - sf:createLifetime(com.intellij.openapi.Disposable):com.jetbrains.rd.util.lifetime.Lifetime
 - sf:createNestedDisposable(com.jetbrains.rd.util.lifetime.Lifetime,java.lang.String):com.intellij.openapi.Disposable
 - bs:createNestedDisposable$default(com.jetbrains.rd.util.lifetime.Lifetime,java.lang.String,I,java.lang.Object):com.intellij.openapi.Disposable

platform/rd-platform-community/src/com/intellij/openapi/rd/LifetimeDisposableEx.kt

@@ -3,12 +3,12 @@ package com.intellij.openapi.rd
 
 import com.intellij.openapi.Disposable
 import com.intellij.openapi.application.WriteIntentReadAction
-import com.intellij.openapi.application.writeIntentReadAction
 import com.intellij.openapi.util.Disposer
 import com.intellij.util.ui.EDT
 import com.jetbrains.rd.util.lifetime.Lifetime
 import com.jetbrains.rd.util.lifetime.LifetimeDefinition
 import com.jetbrains.rd.util.lifetime.isNotAlive
+import java.util.concurrent.atomic.AtomicReference
 
 
 /**
@@ -36,6 +36,29 @@ fun Disposable.defineNestedLifetime(): LifetimeDefinition {
   return lifetimeDefinition
 }
 
+/**
+ * Attaches [this] disposable as a child to [lifetime] such as the disposable will be terminated when [lifetime] terminates.
+ *
+ * When the disposable is disposed of its own, there should be no leaks because the subscription to [lifetime] is also terminated on disposal of [this].
+ */
+fun Disposable.attachAsChildTo(lifetime: Lifetime) {
+  val disposableRef = AtomicReference(this)
+  val childLt = lifetime.createNested()
+  childLt.onTermination {
+    disposableRef.getAndSet(null)?.let {
+      Disposer.dispose(it)
+    }
+  }
+
+  if (!Disposer.tryRegister(this) {
+    disposableRef.getAndSet(null)?.let {
+      childLt.terminate()
+    }
+  }) {
+    childLt.terminate()
+  }
+}
+
 /**
  * Performs an action id this disposable has not been disposed yet.
  * The action receives a lifetime corresponding to this disposable.