Include async:true on async queries

[jdelStrother]

Description of changes

WDYT to something like this? It includes async: true in the payload of ActiveRecord logs if the query is async.

For synchronous queries, I've left the payload as-is (rather than adding async: false), on the assumption that 99% of your queries are probably synchronous, but I don't have a strong feeling either way on that.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[reidmorrison]

@jdelStrother after merging into master, the Rails 8 tests are failing with

ActiveRecord::logs#test_0008_marks async queries with async: true:
ActiveRecord::ActiveRecordError: Can't perform asynchronous queries without a query session
    activerecord (8.0.2) lib/active_record/asynchronous_queries_tracker.rb:50:in 'ActiveRecord::AsynchronousQueriesTracker#current_session'
    activerecord (8.0.2) lib/active_record/core.rb:142:in 'ActiveRecord::Base.asynchronous_queries_session'

I made the test skip the test under rails 8 for now.

[jdelStrother]

I'll take a look when I'm back next week