[pr into #785] Format cleanup

[wild-endeavor]

• Remove the format field from the literal model object since it's no longer in the IDL literal. It's now only in the type.
• Remove file_format field from the python StructuredDataset object. It will default to "parquet", and will only be settable by the user through Annotate. This should be okay because we don't see format to be used too often.
• Add helper functions to decoder/encoder lookup. Default to use "" in case a matching format cannot be found.
• Update remaining handlers to have static values for at least type and format, in some cases also protocol.
• Change the Encoder interface to add structured_literal_type: StructuredDatasetType as an input argument. The reason is because we want contributors to be able to fill in/potentially modify the type information that's embedded in the literal.
• Change the default format in the class-get-item of the python StructuredDataset to also be parquet, otherwise StructuredDataset[my_cols] got a format of "" instead of parquet.
• Make the TransformerEngine fill in missing type information in the literal if not supplied by the encoder.

[codecov]

Codecov Report

Merging #803 (b09f327) into structured-dataset-proposal (15e70b4) will increase coverage by 0.01%.
The diff coverage is 76.74%.

@@                       Coverage Diff                       @@
##           structured-dataset-proposal     #803      +/-   ##
===============================================================
+ Coverage                        85.59%   85.60%   +0.01%     
===============================================================
  Files                              353      353              
  Lines                            30388    30465      +77     
  Branches                          3666     3674       +8     
===============================================================
+ Hits                             26010    26080      +70     
- Misses                            3706     3716      +10     
+ Partials                           672      669       -3     

Impacted Files	Coverage Δ
flytekit/types/structured/bigquery.py	8.77% <0.00%> (-1.65%)	⬇️
tests/flytekit/unit/models/test_literals.py	100.00% <ø> (ø)
flytekit/types/structured/structured_dataset.py	74.10% <73.33%> (+3.67%)	⬆️
flytekit/types/structured/basic_dfs.py	88.13% <91.66%> (+1.34%)	⬆️
...ests/flytekit/unit/core/test_structured_dataset.py	97.64% <95.83%> (-2.36%)	⬇️
flytekit/core/data_persistence.py	70.10% <100.00%> (ø)
flytekit/models/literals.py	98.11% <100.00%> (-0.03%)	⬇️
flytekit/models/types.py	98.83% <100.00%> (+0.02%)	⬆️
...ekit/unit/core/test_structured_dataset_handlers.py	100.00% <100.00%> (ø)
tests/flytekit/unit/core/test_type_engine.py	99.61% <100.00%> (ø)
... and 3 more

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