sudoers: should reject more keywords in alias name position

[japaric]

• CHROOT
• CWD
• NOTAFTER
• NOTBEFORE
• TIMEOUT

relevant tests
https://github.com/memorysafety/sudo-rs/blob/e43a5f00d2c7663b3369ab935f931c360fd70eee/test-framework/sudo-compliance-tests/src/sudoers/runas_alias.rs#L426
https://github.com/memorysafety/sudo-rs/blob/e43a5f00d2c7663b3369ab935f931c360fd70eee/test-framework/sudo-compliance-tests/src/sudoers/host_alias.rs#L248
https://github.com/memorysafety/sudo-rs/blob/e43a5f00d2c7663b3369ab935f931c360fd70eee/test-framework/sudo-compliance-tests/src/sudoers/cmnd_alias.rs#L451
https://github.com/memorysafety/sudo-rs/blob/e43a5f00d2c7663b3369ab935f931c360fd70eee/test-framework/sudo-compliance-tests/src/sudoers/user_list.rs#L377

[dancewithheart]

I opened PR for this: #1565