p4: restore support for <Project> mappings

Perforce roots can't be detected using simple `VcsRootChecker` and have no 'administrative pattern'.
Instead `P4ConnectionCalculator` detects roots and filters them with `RootsConvertor`.
This logic expects `MappingsToRoots` to return all roots from `DefaultVcsRootPolicy`,
without additional filtering by `DefaultVcsRootChecker`.

This fix inherits all issues of old implementation.
A better solution would be to use `P4ConnectionCalculator` instead of
generic root detection/validation logic in `NewMappings`.

Fix regression after f3b725b51c3d09882680ced5f71ab52c75ba9c2d

GitOrigin-RevId: 35d6ea3c76a5d851d40fa28bfab9fc3c2b0ca828

platform/vcs-api/intellij.platform.vcs.iml

@@ -15,5 +15,6 @@
     <orderEntry type="library" name="StreamEx" level="project" />
     <orderEntry type="library" name="JDOM" level="project" />
     <orderEntry type="library" name="kotlin-stdlib-jdk8" level="project" />
+    <orderEntry type="module" module-name="intellij.platform.util" />
   </component>
 </module>

platform/vcs-api/src/com/intellij/openapi/vcs/AbstractVcs.java

@@ -22,10 +22,7 @@ import com.intellij.openapi.vcs.versionBrowser.CommittedChangeList;
 import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.util.ThreeState;
 import com.intellij.util.ui.VcsSynchronousProgressWrapper;
-import org.jetbrains.annotations.CalledInAwt;
-import org.jetbrains.annotations.NonNls;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.*;
 
 import java.util.Collections;
 import java.util.List;
@@ -428,6 +425,11 @@ public abstract class AbstractVcs<ComList extends CommittedChangeList> extends S
     List<VirtualFile> convertRoots(@NotNull List<VirtualFile> result);
   }
 
+  @ApiStatus.Internal
+  public boolean needsLegacyDefaultMappings() {
+    return false;
+  }
+
   /**
    * Returns the implementation of the merge provider which is used to load the revisions to be merged
    * for a particular file.

platform/vcs-impl/src/com/intellij/openapi/vcs/impl/projectlevelman/NewMappings.java

@@ -293,6 +293,8 @@ public class NewMappings implements Disposable {
                                                         @NotNull Collection<VirtualFile> projectRoots,
                                                         @NotNull Set<VirtualFile> mappedDirs) {
     try {
+      if (vcs.needsLegacyDefaultMappings()) return projectRoots;
+
       DirectoryIndex directoryIndex = DirectoryIndex.getInstance(myProject);
       VcsRootChecker rootChecker = myVcsManager.getRootChecker(vcs);