[CLI] Support shorthand for loggers

[carmocca]

What does this PR do?

Fixes #10574

Does your PR introduce any breaking changes? If yes, please list them.

Previous calls with --trainer.logger=pytorch_lightning.loggers.WandbLogger will need to update to --trainer.logger=WandbLogger

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cc @Borda @awaelchli @edward-io @ananthsub @rohitgr7 @kamil-kaczmarek @Raalsky @Blaizzy @carmocca @mauvilsa

[tchaton]

Mind adding a LOGGER_REGISTRY and then all good :)

[tchaton]

LGTM !

[ia-davidpichler]

Is there a way to set the defaults for a custom logger's arguments in code? e.g.

class MyCLI(LightningCLI):
    def add_arguments_to_parser(self, parser) -> None:
        parser.set_defaults({
            "trainer.logger": "TensorBoardLogger",
            "trainer.logger.save_dir": "./logdir/"
        })

[mauvilsa]

Is there a way to set the defaults for a custom logger's arguments in code?

You can do it like:

        parser.set_defaults({
            "trainer.logger": {
                "class_path": "pytorch_lightning.loggers.TensorBoardLogger",
                "init_args": {
                    "save_dir": "./logdir/"
                }
            }
        })