vcs: Refactored "FilePath" implementations not to create new "File" instances on each "getIOFile()" call - reuse same "File" instance created in constructor instead

Otherwise frequent "FilePath.getIOFile()" calls could lead to performance issues. For instance, there are snapshots with slow "Change.isMoved() or Change.isRenamed()" -> "Change.cacheRenameOrMove()" -> "Change.revisionPathsSame()" -> "LocalFilePath.getIOFile()" method calls.

platform/vcs-impl/src/com/intellij/openapi/vcs/FilePathImpl.java

@@ -42,10 +42,12 @@ import java.nio.charset.Charset;
 @Deprecated
 public class FilePathImpl implements FilePath {
   @NotNull private final String myPath;
+  @NotNull private final File myIOFile;
   private final boolean myIsDirectory;
 
   public FilePathImpl(@NotNull String path, boolean isDirectory) {
     myPath = FileUtil.toCanonicalPath(path);
+    myIOFile = new File(myPath);
     myIsDirectory = isDirectory;
   }
   public FilePathImpl(@NotNull VirtualFile file) {
@@ -120,7 +122,7 @@ public class FilePathImpl implements FilePath {
   @Override
   @NotNull
   public File getIOFile() {
-    return new File(myPath);
+    return myIOFile;
   }
 
   @NotNull

platform/vcs-impl/src/com/intellij/openapi/vcs/LocalFilePath.java

@@ -35,10 +35,12 @@ import java.nio.charset.Charset;
 
 public class LocalFilePath implements FilePath {
   @NotNull private final String myPath;
+  @NotNull private final File myIOFile;
   private final boolean myIsDirectory;
 
   public LocalFilePath(@NotNull String path, boolean isDirectory) {
     myPath = FileUtil.toCanonicalPath(path);
+    myIOFile = new File(myPath);
     myIsDirectory = isDirectory;
   }
 
@@ -110,7 +112,7 @@ public class LocalFilePath implements FilePath {
   @Override
   @NotNull
   public File getIOFile() {
-    return new File(myPath);
+    return myIOFile;
   }
 
   @NotNull

platform/vcs-impl/src/com/intellij/openapi/vcs/RemoteFilePath.java

@@ -37,10 +37,12 @@ public class RemoteFilePath implements FilePath {
   private static final TObjectHashingStrategy<String> CASE_SENSITIVE_STRATEGY = FilePathHashingStrategy.create(true);
 
   @NotNull private final String myPath;
+  @NotNull private final File myIOFile;
   private final boolean myIsDirectory;
 
   public RemoteFilePath(@NotNull String path, boolean isDirectory) {
     myPath = path;
+    myIOFile = new File(myPath);
     myIsDirectory = isDirectory;
   }
 
@@ -59,7 +61,7 @@ public class RemoteFilePath implements FilePath {
   @NotNull
   @Override
   public File getIOFile() {
-    return new File(myPath);
+    return myIOFile;
   }
 
   @NotNull