cipher:dilithium: Make the implementation into three files.
* cipher/dilithium-common.c: New. Common part. * cipher/dilithium-dep.c: New. DILITHIUM_MODE dependent part. * cipher/dilithium.c: Move functions and variables to two files.
- GnuPG-bug-id: T7640
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>