[diagrams] Improve removing multiple elements in API v2

In this commit, I added additional methods `removeNodes`, `removeEdges`, `removeGroupNodes` inside `DiagramDataModel`. This is more convenient for external developers, as they don't have to manually group multiple elements.

GitOrigin-RevId: 99a49fbd5ee1b0c740f06b033c708366b21df6f0

platform/core-impl/src/com/intellij/util/graph/impl/HierarchyTreeImpl.kt

@@ -23,7 +23,8 @@ class HierarchyTreeImpl<N : Any, GN : N> : HierarchyTree<N, GN> {
   private val nodes2ParentGroupsMap = mutableMapOf<N, GN>()
   private val groupNodes2Children = mutableMapOf<GN, MutableSet<N>>()
 
-  override fun getAllHierarchyNodes(): Set<N> = hierarchyNodes
+  override val allHierarchyNodes: Set<N>
+    get() = hierarchyNodes
 
   override fun getParent(node: N): GN? {
     return nodes2ParentGroupsMap[node]
@@ -43,6 +44,16 @@ class HierarchyTreeImpl<N : Any, GN : N> : HierarchyTree<N, GN> {
     return children
   }
 
+  override fun getDepth(node: N): Int {
+    var depth = 0
+    var parent = getParent(node)
+    while (parent != null) {
+      depth++
+      parent = getParent(parent)
+    }
+    return depth
+  }
+
   override fun connect(child: N, parent: GN) {
     hierarchyNodes.add(child)
     hierarchyNodes.add(parent)

platform/util/src/com/intellij/util/graph/HierarchyTree.kt

@@ -29,7 +29,7 @@ interface HierarchyTree<N : Any, GN : N> {
    *
    * @return The set containing all the hierarchy nodes in the hierarchy tree.
    */
-  fun getAllHierarchyNodes(): Set<N>
+  val allHierarchyNodes: Set<N>
 
   /**
    * Retrieves the parent node of the given node.
@@ -49,6 +49,14 @@ interface HierarchyTree<N : Any, GN : N> {
    */
   fun getChildren(group: GN, isRecursively: Boolean = false): Set<N>
 
+  /**
+   * Retrieves the depth of the given node in the hierarchy tree.
+   *
+   * @param node The node for which to retrieve the depth.
+   * @return The depth of the given node in the hierarchy tree.
+   */
+  fun getDepth(node: N): Int
+
   /**
    * Connects a child node to a parent group node in the hierarchy tree.
    *