vcs: skip the "vendor" dir from root detection (IDEA-199926)

It often contains template libraries downloaded e.g. by Composer framework.

platform/util/resources/misc/registry.properties

@@ -527,6 +527,8 @@ vcs.history.refine.description=Use a refining algorithm on file history that eli
 vcs.executable.validator.timeout.sec=60
 vcs.root.detector.folder.depth=-1
 vcs.root.detector.folder.depth.description=How deep should the IDE scan the file tree, searching for Git/Hg roots in the project. Set to -1 to scan the whole file tree.
+vcs.root.detector.skip.vendor=true
+vcs.root.detector.skip.vendor.description=If true, Git/Hg roots won't be detected under directories called 'vendor'. 
 vcs.root.auto.add=true
 vcs.root.auto.add.description=Automatically register detected Git/Hg roots.
 vcs.root.auto.add.nofity=false

platform/vcs-impl/src/com/intellij/openapi/vcs/roots/VcsRootDetectorImpl.java

@@ -5,6 +5,7 @@ import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.progress.ProgressManager;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.roots.ProjectRootManager;
+import com.intellij.openapi.util.registry.Registry;
 import com.intellij.openapi.vcs.AbstractVcs;
 import com.intellij.openapi.vcs.ProjectLevelVcsManager;
 import com.intellij.openapi.vcs.VcsRoot;
@@ -18,6 +19,7 @@ import org.jetbrains.annotations.Nullable;
 import java.util.*;
 
 import static com.intellij.openapi.vfs.VirtualFileVisitor.CONTINUE;
+import static com.intellij.openapi.vfs.VirtualFileVisitor.SKIP_CHILDREN;
 
 public class VcsRootDetectorImpl implements VcsRootDetector {
   private static final Logger LOG = Logger.getInstance(VcsRootDetectorImpl.class);
@@ -103,6 +105,7 @@ public class VcsRootDetectorImpl implements VcsRootDetector {
   private Set<VcsRoot> scanForRootsInsideDir(@NotNull VirtualFile root) {
     Set<VcsRoot> roots = new HashSet<>();
     VcsRootScanner.visitDirsRecursivelyWithoutExcluded(myProject, myProjectManager, root, dir -> {
+      if (Registry.is("vcs.root.detector.skip.vendor") && dir.getName().equalsIgnoreCase("vendor")) return SKIP_CHILDREN;
       AbstractVcs vcs = getVcsFor(dir);
       if (vcs != null) {
         LOG.debug("Found VCS " + vcs + " in " + dir);

platform/vcs-tests/testSrc/com/intellij/openapi/vcs/roots/VcsRootDetectorTest.kt

@@ -125,6 +125,13 @@ class VcsRootDetectorTest : VcsRootBaseTest() {
     expect(roots[0])
   }
 
+  fun `test dont scan inside vendor folder`() {
+    projectRoot.initRepository()
+    createVcsRoots("vendor", "vendor/child/child")
+
+    expect(projectRoot)
+  }
+
   private fun createVcsRoots(vararg relativePaths: String) = createVcsRoots(listOf(*relativePaths))
 
   private fun createVcsRoots(relativePaths: Collection<String>): List<VirtualFile> {