Remove the FeatureVector annotation type, various fixes, and cleanup

[gdlg]

This pull request removes support for the deprecated FeatureVector annotation type and related functionality, add missing plugin definitions to spec.json. It also updates documentation and test configurations to reflect these changes.

Removal of FeatureVector annotation type and related functionality

• Removed the FeatureVector annotation class, its matcher and merger classes, and the corresponding feature_vector entry from the AnnotationType enum in src/datumaro/components/annotation.py, src/datumaro/components/annotations/matcher.py, and src/datumaro/components/annotations/merger.py. [1] [2] [3] [4] [5] [6] [7] [8] [9]
• Removed references to FeatureVectorMerger from the merge logic in src/datumaro/components/merge/intersect_merge.py. [1] [2]
• Updated tests to remove checks for feature_vector statistics in tests/unit/operations/test_statistics.py. [1] [2]

Plugin additions for new formats

• Added plugin definitions for Roboflow TFRecord and TensorFlow Detection API formats (DatasetBase, Importer, and Exporter) to src/datumaro/plugins/specs.json, including TensorFlow as an extra dependency. [1] [2]

Documentation and compatibility updates

• Removed deprecated usage examples for project-based workflows from docs/source/docs/data-formats/media_formats.md and deleted the deprecated src/datumaro/project.py module. [1] [2]
• Cleaned up deprecated variable declarations from CLI and annotation modules. [1] [2] [3] [4]

Test configuration updates

• Updated tox.ini to include TensorFlow and TFDS for Python 3.12 environments.

How to test

Checklist

• I have added unit tests to cover my changes.​
• I have added integration tests to cover my changes.​
• I have added the description of my changes into CHANGELOG.​
• I have updated the documentation accordingly

License

• I submit my code changes under the same MIT License that covers the project.
  Feel free to contact the maintainers if that's a concern.
• I have updated the license header for each file (see an example below).

# Copyright (C) 2025 Intel Corporation
#
# SPDX-License-Identifier: MIT