Add engine for fluent to master

[mchugh19]

What does this PR do?

Master port of #51942
Adds new engine to export events to fluentd

What issues does this PR fix or reference?

None

Tests written?

No - as discussed in PR #51942...

Having a bit of trouble here. The other engine test examples are the sqs engine which validates sqs messages can be resent on the salt event bus, while the slack tests validate the complex configuration. For the fluent engine, it really is just:

while True:
    salt_event = event_bus.get_event_block()
    if salt_event:
        event.Event(app, salt_event)

where I'm struggling to come up with a meaningful test. As long as the fluent event module is functional, and the event_bus.get_event_block() works as expected, there isn't much else to validate here.

Commits signed with GPG?

No

[dwoz]

@mchugh19 Can you please rebase to the current head of master and resolve the change log conflicts?

[mchugh19]

Resolved conflicts on release notes

[dwoz]

@mchugh19 Please have a look at the docs failure.

[mchugh19]

@dwoz docs should be better. Go go jenkins doc build

[dwoz]

re-run full centos