FCM user notifcations should not fail if "no longer existing types" stored on the DB

[quantranhong1999]

Why

GIVEN at first TMail support a change type e.g. Thread, and user register updates for the Thread changes via FirebaseSubscription/set.
WHEN TMail gives up supporting the Thread change type
THEN:

• FirebaseSubscription/get likely would fail as TypeStateFactory fails to parse the Thread type from DB
• FirebasePushListener likely would fail as TypeStateFactory fails to parse the Thread type from DB

Expect: Should not fail if DB contains the "no longer existing types".

How

Be more lenient in TypeStateFactory: skip the parsing failure upon retrieval phase and a WARN level log cf: #956 (comment)

Notes

Could contribute this to PushSubscription on James side if suitable...

[chibenwa]

Idem for PushSubscriptions / james push?
(& JIRA ticket?)