feature: Add logging test / val callback functions

[tchaton]

What does this PR do?

This PR adds logic to add logging for test / val callbacks.

Fixes # (issue)

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[pep8speaks]

Hello @tchaton! Thanks for opening this PR.

• In the file pytorch_lightning/trainer/connectors/logger_connector.py:

Line 211:1: W293 blank line contains whitespace

• In the file pytorch_lightning/trainer/connectors/logger_connector_utils/__init__.py:

Line 2:121: E501 line too long (123 > 120 characters)

• In the file pytorch_lightning/trainer/connectors/logger_connector_utils/cache_metrics.py:

Line 49:121: E501 line too long (126 > 120 characters)
Line 49:127: W291 trailing whitespace
Line 53:82: W292 no newline at end of file

• In the file pytorch_lightning/trainer/evaluation_loop.py:

Line 251:36: W291 trailing whitespace

• In the file tests/trainer/logging/test_eval_loop_logging_1_0.py:

Line 384:121: E501 line too long (124 > 120 characters)
Line 388:1: W293 blank line contains whitespace
Line 394:121: E501 line too long (125 > 120 characters)
Line 553:121: E501 line too long (124 > 120 characters)
Line 562:121: E501 line too long (125 > 120 characters)
Line 714:82: W292 no newline at end of file

Do see the Hitchhiker's guide to code style

[Borda]

@tchaton this is the parent PR for all the smaller children, right? #4439 #4495

[stale]

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[stale]

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