ANDROID: crypto: shash - Add crypto_grab_shash() and crypto_spawn_shash_alg()

Analogous to crypto_grab_skcipher() and crypto_spawn_skcipher_alg(),
these are useful for algorithms that need to use a shash sub-algorithm,
possibly in addition to other sub-algorithms.

Bug: 32975945
Signed-off-by: Eric Biggers <ebiggers@google.com>
Change-Id: I44e5a519d73f5f839e3b6ecbf8c66e36ec569557