[Feature] Support Objects365 Dataset

[BIGWangYuDong]

Support Objects365v1 and Objects365v2

[codecov]

Codecov Report

Base: 64.15% // Head: 63.90% // Decreases project coverage by -0.25% ⚠️

Coverage data is based on head (bb2a110) compared to base (cc9513f).
Patch coverage: 25.33% of modified lines in pull request are covered.

❗ Current head bb2a110 differs from pull request most recent head a141fb4. Consider uploading reports for the commit a141fb4 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #7525      +/-   ##
==========================================
- Coverage   64.15%   63.90%   -0.26%     
==========================================
  Files         361      347      -14     
  Lines       29585    28187    -1398     
  Branches     5033     4755     -278     
==========================================
- Hits        18981    18012     -969     
+ Misses       9600     9219     -381     
+ Partials     1004      956      -48     

Flag	Coverage Δ
unittests	63.90% <25.33%> (-0.23%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
mmdet/core/evaluation/__init__.py	100.00% <ø> (ø)
mmdet/datasets/objects365.py	22.85% <22.85%> (ø)
mmdet/core/evaluation/class_names.py	39.39% <50.00%> (+1.46%)	⬆️
mmdet/datasets/__init__.py	100.00% <100.00%> (ø)
mmdet/models/necks/nas_fpn.py	14.28% <0.00%> (-57.15%)	⬇️
mmdet/models/detectors/yolox.py	28.57% <0.00%> (-51.03%)	⬇️
mmdet/models/necks/nasfcos_fpn.py	15.49% <0.00%> (-49.30%)	⬇️
mmdet/models/necks/fpg.py	11.41% <0.00%> (-48.92%)	⬇️
mmdet/models/necks/fpn_carafe.py	10.71% <0.00%> (-33.93%)	⬇️
mmdet/utils/setup_env.py	72.72% <0.00%> (-19.28%)	⬇️
... and 69 more

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[RangiLyu]

LGTM. Can be merged after fixing typo.