[indic] Treat Consonant_With_Stacker as consonant

Fixes https://github.com/behdad/harfbuzz/issues/528
"Kannada JIHVAMULIYA and UPADHMANIYA insert dotted circles"

Bug: 65266006
Test: Manual
Change-Id: I5fcc82096323a35aaa37becdd209d5973333bb64
3 files changed