Apisix plugin - support case Redis down

[vttranlina]

Context

In the tmail-apisix-plugin-runner plugin, we currently have a TokenRevokedFilter. This filter is responsible for checking whether the token in the request has been revoked previously by querying Redis.
The issue arises when Redis is down, causing the checking process to take a significant amount of time and resulting in the inability to perform login and logout flows.

Ref: #1013

How to resolve it

• Add a parameter ignoreRedisErrors (defaulting to false), it can be configurable. If turned to true, if redis fails we ignore the logout flow, effectively preserving the service at a cost of a bit of security.

DOD

• Add test case at com.linagora.apisix.plugin.RedisRevokedTokenRepositoryTest
• Document

[vttranlina]

pr #1025