Dashboards: Add collection and presentation for SHUNNED_REPLICATION_LAG state to proxysql_connection_pool_status

User Impact: Users cannot see all possible statuses
Backend servers can have status SHUNNED_REPLICATION_LAG in table stats_mysql_connection_pool.
Now only next states are collected:

• ONLINE

• SHUNNED

• OFFLINE_SOFT

• OFFLINE_HARD

So it's not possible get any status of an instance if it has the uncollected status.

Reference: https://github.com/sysown/proxysql/blob/v2.0.15/lib/MySQL_HostGroups_Manager.cpp#L3191

Also it's required to add changes on dashboard "ProxySQL Instance Summary", element: "Endpoint Status"

Expected result: All possible statuses are collected and shown on the dashboard.