Harmonize both Trainers API
Author: sgugger
Pull request: yes

As discussed after the latest rework of TFTrainer.

Also removed references to "master" processes in our API to go to main with deprecation warnings.

Comments:
# [Codecov](https://codecov.io/gh/huggingface/transformers/pull/6157?src=pr&el=h1) Report
> Merging [#6157](https://codecov.io/gh/huggingface/transformers/pull/6157?src=pr&el=desc) into [master](https://codecov.io/gh/huggingface/transformers/commit/ec0267475c16a1913e64cb4f81fd54d153e3d815&el=desc) will **increase** coverage by `0.40%`.
> The diff coverage is `67.47%`.

[![Impacted file tree graph](https://codecov.io/gh/huggingface/transformers/pull/6157/graphs/tree.svg?width=650&height=150&src=pr&token=9qOlN6Hb1c)](https://codecov.io/gh/huggingface/transformers/pull/6157?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master    #6157      +/-   ##
==========================================
+ Coverage   79.38%   79.79%   +0.40%     
==========================================
  Files         146      146              
  Lines       26454    26607     +153     
==========================================
+ Hits        21001    21230     +229     
+ Misses       5453     5377      -76     
```


| [Impacted Files](https://codecov.io/gh/huggingface/transformers/pull/6157?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [src/transformers/\_\_init\_\_.py](https://codecov.io/gh/huggingface/transformers/pull/6157/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9fX2luaXRfXy5weQ==) | `99.24% <ø> (ø)` | |
| [src/transformers/benchmark/benchmark\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/6157/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9iZW5jaG1hcmsvYmVuY2htYXJrX3V0aWxzLnB5) | `69.50% <ø> (ø)` | |
| [src/transformers/modeling\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/6157/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ191dGlscy5weQ==) | `87.35% <ø> (ø)` | |
| [src/transformers/tokenization\_bert\_japanese.py](https://codecov.io/gh/huggingface/transformers/pull/6157/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy90b2tlbml6YXRpb25fYmVydF9qYXBhbmVzZS5weQ==) | `32.05% <0.00%> (+1.56%)` | :arrow_up: |
| [src/transformers/trainer\_tf.py](https://codecov.io/gh/huggingface/transformers/pull/6157/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy90cmFpbmVyX3RmLnB5) | `13.09% <ø> (-3.05%)` | :arrow_down: |
| [src/transformers/trainer.py](https://codecov.io/gh/huggingface/transformers/pull/6157/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy90cmFpbmVyLnB5) | `39.14% <23.94%> (-1.83%)` | :arrow_down: |
| [src/transformers/pipelines.py](https://codecov.io/gh/huggingface/transformers/pull/6157/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9waXBlbGluZXMucHk=) | `79.36% <84.34%> (+0.86%)` | :arrow_up: |
| [src/transformers/tokenization\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/6157/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy90b2tlbml6YXRpb25fdXRpbHMucHk=) | `90.40% <88.88%> (+0.44%)` | :arrow_up: |
| [src/transformers/hf\_argparser.py](https://codecov.io/gh/huggingface/transformers/pull/6157/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9oZl9hcmdwYXJzZXIucHk=) | `69.23% <100.00%> (+2.96%)` | :arrow_up: |
| [src/transformers/tokenization\_utils\_base.py](https://codecov.io/gh/huggingface/transformers/pull/6157/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy90b2tlbml6YXRpb25fdXRpbHNfYmFzZS5weQ==) | `93.83% <100.00%> (+1.39%)` | :arrow_up: |
| ... and [11 more](https://codecov.io/gh/huggingface/transformers/pull/6157/diff?src=pr&el=tree-more) | |

------

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> Powered by [Codecov](https://codecov.io/gh/huggingface/transformers/pull/6157?src=pr&el=footer). Last update [603cd81...d95e283](https://codecov.io/gh/huggingface/transformers/pull/6157?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).