add selinux rules for mini-keyctl

mini-keyctl is a binary used to load channel keys to .fsverity keyring.
This CL creates a new domain for mini-keyctl and a type for /proc/keys
and adds allow rules needed by this binary.

Bug: 112038861
Test: manual
Merged-In: I3b744d302859a02dfe63c81c7f33bb30912d7994
Change-Id: I3b744d302859a02dfe63c81c7f33bb30912d7994
diff --git a/private/genfs_contexts b/private/genfs_contexts
index 87b9cb3..2a74484 100644
--- a/private/genfs_contexts
+++ b/private/genfs_contexts
@@ -10,6 +10,7 @@
 genfscon proc /filesystems u:object_r:proc_filesystems:s0
 genfscon proc /interrupts u:object_r:proc_interrupts:s0
 genfscon proc /iomem u:object_r:proc_iomem:s0
+genfscon proc /keys u:object_r:proc_keys:s0
 genfscon proc /kmsg u:object_r:proc_kmsg:s0
 genfscon proc /loadavg u:object_r:proc_loadavg:s0
 genfscon proc /meminfo u:object_r:proc_meminfo:s0