test: Add directory symlink to tests/itest/

Additionally, the test output was regenerated using "just idump".
Note that manual edits are necessary to ensure the absolute path in
tests/cmd/ starts with "[CWD]".

tests/cmd/absolute_recurse_unix.stdout

@@ -2,6 +2,7 @@
 [CWD]/tests/itest/b
 [CWD]/tests/itest/c
 [CWD]/tests/itest/d
+[CWD]/tests/itest/dir-symlink -> vagrant/debug
 [CWD]/tests/itest/e
 [CWD]/tests/itest/exa
 [CWD]/tests/itest/f

tests/cmd/absolute_unix.stdout

@@ -2,6 +2,7 @@
 [CWD]/tests/itest/b
 [CWD]/tests/itest/c
 [CWD]/tests/itest/d
+[CWD]/tests/itest/dir-symlink -> vagrant/debug
 [CWD]/tests/itest/e
 [CWD]/tests/itest/exa
 [CWD]/tests/itest/f

tests/cmd/basic_all.stdout

@@ -2,6 +2,7 @@ a
 b
 c
 d
+dir-symlink -> vagrant/debug
 e
 exa
 f

tests/cmd/icons_all.stdout

@@ -2,6 +2,7 @@
  b
  c
  d
+ dir-symlink -> vagrant/debug
  e
  exa
  f

tests/cmd/long_windows.stdout

@@ -2,6 +2,7 @@
 -a--- b
 -a--- c
 -a--- d
+l---- dir-symlink -> vagrant/debug
 -a--- e
 d---- exa
 -a--- f

tests/gen/absolute_recurse_unix.stdout

@@ -2,6 +2,7 @@
 /build/source/tests/itest/b
 /build/source/tests/itest/c
 /build/source/tests/itest/d
+/build/source/tests/itest/dir-symlink -> vagrant/debug
 /build/source/tests/itest/e
 /build/source/tests/itest/exa
 /build/source/tests/itest/f

tests/gen/absolute_unix.stdout

@@ -2,6 +2,7 @@
 /build/source/tests/itest/b
 /build/source/tests/itest/c
 /build/source/tests/itest/d
+/build/source/tests/itest/dir-symlink -> vagrant/debug
 /build/source/tests/itest/e
 /build/source/tests/itest/exa
 /build/source/tests/itest/f

tests/itest/dir-symlink

@@ -0,0 +1 @@
+vagrant/debug