Allow Redis usage with username

[ZakarFin]

Also adds credentials handling for the redis-session profile and cache syncing for clustered environments. After this it's possible to configure one or both as Redis credentials on oskari-ext.properties:

redis.user=user
redis.password=passwd

If these properties are not defined the code will work like without credentials. If you have the keys with empty values, things will probably not work.

Previously a password could be configured the basic Redis connectivity, but it wasn't used for storing/accessing session information on the redis-session profile (this didn't work at all for redis-server that requires credentials resulting in exception like NOPERM this user has no permissions to access one of the keys used as arguments.) or for the pub/sub functionality that the caching uses for syncing changes between servers. Password can be configured on Redis versions <6 and the user can be used on 6+.

https://redis.io/docs/latest/operate/oss_and_stack/management/security/acl/

This allows for example creating a user named user with password passwd on redis-cli:

ACL SETUSER user on >passwd ~* +@all

With ~* meaning access to all keys and +@all means access to all commands. On Redis 6.2 there is also &* which means pub/sub for anything and it might be required for the cache syncing.

[ZakarFin]

Looks like &* is not required for cluster communication even on Redis 6.2.