Move transformer impl to flava folder

[ankitade]

Summary:
Only used by flava so moving it to that folder to make space for the other transformer. will rename to flava transformer in a followup

Test plan:
pytest tests/
sanity check
torchrun --nproc_per_node=1 -m flava.native.train config=flava/native/configs/pretrain_debug.yaml

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@ankitade has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[codecov-commenter]

Codecov Report

Patch coverage: 97.61% and no project coverage change.

Comparison is base (97264a2) 68.72% compared to head (9b2f295) 68.72%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #439   +/-   ##
=======================================
  Coverage   68.72%   68.72%           
=======================================
  Files         169      169           
  Lines       11376    11374    -2     
=======================================
- Hits         7818     7817    -1     
+ Misses       3558     3557    -1     

Files Changed	Coverage Δ
examples/flava/native/train.py	0.00% <0.00%> (ø)
torchmultimodal/models/flava/transformer.py	97.22% <98.52%> (+2.10%)	⬆️
tests/models/flava/test_image_encoder.py	100.00% <100.00%> (ø)
tests/models/flava/test_text_encoder.py	100.00% <100.00%> (ø)
tests/models/flava/test_transformer.py	100.00% <100.00%> (ø)
torchmultimodal/models/flava/image_encoder.py	75.00% <100.00%> (ø)
torchmultimodal/models/flava/model.py	95.57% <100.00%> (ø)
torchmultimodal/models/flava/text_encoder.py	100.00% <100.00%> (ø)
...chmultimodal/modules/encoders/bert_text_encoder.py	90.47% <100.00%> (+0.23%)	⬆️
torchmultimodal/modules/layers/transformer.py	100.00% <100.00%> (+1.33%)	⬆️

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@ankitade has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[facebook-github-bot]

@ankitade merged this pull request in 1aa2ed2.