Move descriptor hashing to `mirror::Class`. am: 10137abcd0 am: 40f266c78c am: 23c85b0bee am: 8f4f068182 am: 64f006ef5c

Original change: https://android-review.googlesource.com/c/platform/art/+/2067131

Change-Id: I86a9f42fdb60a14896d7e4f9fe89c2e34b991bc1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>