Security patch fixes

[steve-chavez]

Allows using configurable roles like:

reserved_roles = "anon*, authenticator*"

<role*> here means that the role can have GUCs and placeholders configured by the supautils.privileged_role, so it can do:

• alter role anon set statement_timeout = '15s' (ref) - c8efcd7
• grant testme to authenticator(ref, also affects custom db roles) - b3a6e95

Configurable roles cannot be dropped or renamed by the privileged_role though.

Also allows using wildcards on placeholders defined on privileged_role_allowed_configs = "pgrst.*", this solves:

• alter role authenticator set pgrst.db_plan_enabled to true(ref) - 146155e

Otherwise we'd have to whitelist all possible placeholders.

[soedirgo]

Added some minor changes - LGTM!