mod_authz_internal: Fix warning due to global use Thanks Menel and Martin

Backed out changeset 1bc2220cd6ec The use of the error helpers creates an `<error/>` child element containing the error condition. This is however not allowed as per XEP-0198, which specifies that the error condition is to be a direct child of the `<failed/>` stream management element. This has triggered a fun reconnect loop in aioxmpp where it was reported by a user [1]. [1]: https://github.com/horazont/aioxmpp/issues/382

util.jwt: More robust ECDSA signature parsing, fail early on unexpected length

util.crypto: Fix tests Found this number in a hat. Sleepy time. Good night.

util.jwt: Add support for ES512 (+ tests)

util.crypto, util.jwt: Generate consistent signature sizes (via padding) This fixes the signature parsing and building to work correctly. Sometimes a signature was one or two bytes too short, and needed to be padded. OpenSSL can do this for us.

CHANGES: Update with MUC permission changes

mod_authz_internal: Allow specifying default role for public (remote) users

Backed out changeset 73a45ba6e3f1 in favour of 427dd01f0864 New behaviour (muc_room_allow_persistent = true, the default): - Parent host users are not restricted by default (prosody:user) - Users without roles (by default that is non-admins, non-parent-host users, and users on other servers) can no longer configure persistence by default. muc_room_allow_persistent = false will restrict persistence to prosody:admin. Parent-host users should not be restricted by default, and this can be configured via the new roles/permissions options.

mod_muc: Better map restrict_room_creation to role permissions (behaviour change) With this change and 427dd01f0864, room creation is now effectively restricted to parent-host users by default. This is a better default than previous Prosody versions (where room creation was not restricted). The "local" option for restrict_room_creation is no longer used (any value other than true/false won't change the default behaviour). restrict_room_creation = true will grant prosody:admin the ability to create rooms. restrict_room_creation = false disables all permission checks. Anything between these two can be achieved using custom roles and permissions.