EV 355: part II: update schemas and enforce required property

[klemmpnx]

This PR:

• update OCPP 201 standardized schema via script:
• add variable WebsocketPongTimeout in schema (already used in ChargePoint / manually added to
• corrects usage of required "SecurityCtrlrIdentity" in "SecurityCtrlr" (key must be property key not variable name)
• add new struct RequiredComponentVariable as subclass of ComponentVariable for required variables (via script)
• adjust usages in ChargePoint:
  • get_latest_meter_value_filtered requires "RequiredComponentVariable" (no further adaptions required)
  • authorize_req does not set cacheExpiryDateTime if AuthCacheLifeTime not set (in accordance with spec; this would have failed before if this non-required variable had not been given)

[klemmpnx]

@Pietfried : applied your changes, rebased and tested again

[Pietfried]

default ciphersuites have been changed in the meantime:
#274