Move File.stat() -> Stat.path().

Thanks, Michel!

test/io/stat/path_directory.wren

@@ -0,0 +1,16 @@
+import "io" for Stat
+import "scheduler" for Scheduler
+
+var stat = Stat.path("test/io/directory/dir")
+
+System.print(stat is Stat)            // expect: true
+System.print(stat.device is Num)      // expect: true
+System.print(stat.inode is Num)       // expect: true
+System.print(stat.mode is Num)        // expect: true
+System.print(stat.linkCount >= 1)     // expect: true
+System.print(stat.user is Num)        // expect: true
+System.print(stat.group is Num)       // expect: true
+System.print(stat.specialDevice)      // expect: 0
+System.print(stat.size > 0)           // expect: true
+System.print(stat.blockSize is Num)   // expect: true
+System.print(stat.blockCount is Num)  // expect: true