When `rails console` or `rails server` are used along with a logger set to output to `STDOUT` then the contents will show up twice. This happens because the logger is extended with `ActiveSupportLogger.broadcast` with a destination of STDOUT even if it is already outputting to `STDOUT`.
Previously PR #22592 attempted to fix this issue, but it ended up causing NoMethodErrors. A better approach than relying on adding a method and flow control is to inspect the log destination directly. For this `ActiveSupport::Logger.logger_outputs_to?` was introduced
```ruby
logger = Logger.new(STDOUT)
ActiveSupport::Logger.logger_outputs_to?(logger, STDOUT)
# => true
```
To accomplish this we must look inside of an instance variable of standard lib's Logger `@logdev`. There is a related Ruby proposal to expose this method in a standard way: https://bugs.ruby-lang.org/issues/11955
- uses instance defined level if no custom local log level defined
- Keeps track of local log level per [ thread + object-instance ]
- prevents memory leakage by removing local level hash key/value on #silence method exit
- avoids the use of Thread local variables
