Pass exceptions from the ExceptionListener to Monolog for logging

| Q             | A
| ------------- | ---
| Bug fix?      | rather yes
| New feature?  | rather no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #7973, #7976
| License       | MIT
| Doc PR        | n/a

Pass exceptions caught by the ExceptionListener to Monolog, using the log message context. As of Monolog 1.5, exceptions passed that way will at least be logged with the line they were thrown in, also including any previous exceptions. 

Getting full stack traces (as suggested in #7976) becomes a possible change at the Monolog level (see seldaek/monolog#192) or users can add their own Monolog Formatter for that.