[Rachana] Use Reference glyphs (scaled) for stacked forms of യ്ച്ച, ല്ച്ച, ഴ്ച്ച

Signed-off-by: Rajeesh K Nambiar <rajeeshknambiar@gmail.com>
[Rachana] Homogenize size of ച്ച in യ്ച്ച, ല്ച്ച and ഴ്ച്ച

Signed-off-by: Rajeesh K Nambiar <rajeeshknambiar@gmail.com>
[Rachana] Minor glyph position adjustment for യ്ച്ച , ല്ച്ച, ഴ്ച്ച