[RFE] Ability to disable non-etm MACs

1. DEFAULT policy has the same MACs as before, ETM and non-ETM (and implicit, but that's not controlled by macs option) 2. FIPS:OSPP uses etm@ssh = DISABLE_ETM has only non-ETM macs as before (and implicit) 3. specifying etm@ssh = DISABLE_NON_ETM and has ETM macs (and implicit) 4. ssh_etm = 1 works as before and outputs a deprecation warning 5. ssh_etm = 0 works as before and outputs a deprecation warning 6. it's documented in the manpages that the option is only meant to be used with the SSH scope

.Finer control over MACs in SSH with `crypto-policies` You can now set additional options for message authentication codes (MACs) for the SSH protocol in the system-wide cryptographic policies (`crypto-policies`). With this update, the `crypto-policies` option `ssh_etm` has been converted into a tri-state ` etm@SSH ` option. The previous `ssh_etm` option has been deprecated. You can now set `ssh_etm` to one of the following values: `ANY`:: Allows both `encrypt-then-mac` and `encrypt-and-mac` MACs. `DISABLE_ETM`:: Disallows `encrypt-then-mac` MACs. `DISABLE_NON_ETM`:: Disallows MACs that do not use `encrypt-then-mac`. Note that ciphers that use implicit MACs are always allowed because they use authenticated encryption.