More file system checking functions:

- Stat#isFile
- Stat#isDirectory
- Directory.exists()
- File.exists()

test/io/stat/is_directory.wren

@@ -0,0 +1,4 @@
+import "io" for Stat
+
+System.print(Stat.path("test/io/file/file.txt").isDirectory) // expect: false
+System.print(Stat.path("test").isDirectory) // expect: true

test/io/stat/is_file.wren

@@ -0,0 +1,4 @@
+import "io" for Stat
+
+System.print(Stat.path("test/io/file/file.txt").isFile) // expect: true
+System.print(Stat.path("test").isFile) // expect: false

test/io/stat/path.wren

@@ -1,5 +1,4 @@
 import "io" for Stat
-import "scheduler" for Scheduler
 
 var stat = Stat.path("test/io/file/file.txt")
 

test/io/stat/path_directory.wren

@@ -1,5 +1,4 @@
 import "io" for Stat
-import "scheduler" for Scheduler
 
 var stat = Stat.path("test/io/directory/dir")