Support Depedency loading checks for arbitrary dependencies

[moxious]

Relates to:

Zendesk Ticket https://neotechnology.zendesk.com/agent/tickets/11765

The issue:

Neo4j-streams can currently check if APOC is loaded before starting, but customer needs the same functionality for custom plugins.

Options:

• Use dbms.procedures() / dbms.functions() to check for whether certain procs are loaded. SHOW FUNCTIONS/SHOW PROCEDURES may be necesary in future 4+ releases
• Permit custom cypher query, which must return non-false value

[moxious]

We want the cypher approach; need to implement a method of specifying a polling startup query & timeout similar to what was done with APOC previous.

[moxious]

this is unlikely to be worked on because of coming plugin deprecation in favor of kafka connect source implementation