Add test cases for Thai PUA shaping

test/shaping/texts/in-tree/shaper-thai/script-thai/misc/MANIFEST

diff --git a/test/shaping/texts/in-tree/shaper-thai/script-thai/misc/MANIFEST b/test/shaping/texts/in-tree/shaper-thai/script-thai/misc/MANIFEST
index 6aa865b..911099e 100644
--- a/test/shaping/texts/in-tree/shaper-thai/script-thai/misc/MANIFEST
+++ b/test/shaping/texts/in-tree/shaper-thai/script-thai/misc/MANIFEST
@@ -1,2 +1,3 @@
 phinthu.txt
+pua-shaping.txt
 sara-am.txt

test/shaping/texts/in-tree/shaper-thai/script-thai/misc/pua-shaping.txt

diff --git a/test/shaping/texts/in-tree/shaper-thai/script-thai/misc/pua-shaping.txt b/test/shaping/texts/in-tree/shaper-thai/script-thai/misc/pua-shaping.txt
new file mode 100644
index 0000000..c17834b
--- /dev/null
+++ b/test/shaping/texts/in-tree/shaper-thai/script-thai/misc/pua-shaping.txt
@@ -0,0 +1,11 @@
+นี
+น่
+นี่
+น่ี
+ป็
+ญ
+ญุ
+ฝิ
+ฝิ่
+ฝ่
+ฎู