Deprecate prepare_data_per_node flag on Trainer and set it as a property for DataHooks

[ninginthecloud]

What does this PR do?

Fixes #8733
This PR has completed the following:

1. add DataHooks with prepare_data_per_node property
2. set prepare_data_per_node in trainer as optional
3. update on_trainer_init function in data_connector class
4. update tests: test_datamodules.py and test_hooks.py
5. update prepare_data() implementation and remove can_prepare_data() in data_connector class
6. user can handle prepare_data in lightningmodule and lightningdatamodule independently.

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

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[codecov]

Codecov Report

Merging #8958 (702cdc8) into master (8a93173) will decrease coverage by 4%.
The diff coverage is 96%.

@@           Coverage Diff           @@
##           master   #8958    +/-   ##
=======================================
- Coverage      93%     89%    -4%     
=======================================
  Files         175     175            
  Lines       14379   14391    +12     
=======================================
- Hits        13322   12749   -573     
- Misses       1057    1642   +585     

[ninginthecloud]

This PR needs rebase, I will update soon.

[tchaton]

Dear @ninginthecloud,

Let's use human readable title for PR :)

Best,
T.C

[tchaton]

LGTM !