[Feature] Support InShop Dataset (Image Retrieval).

[zzc98]

Motivation

Support InShop dataset .

Example

>>> from mmcls.data import InShop

>>> data_root = 'data/stanfordcars'
>>> inshop_train_cfg = dict(data_root='data/inshop', mode='train')
>>> inshop_train = InShop(**inshop_train_cfg)
>>> len(inshop_train)
25882
>>> inshop_query_cfg = dict(data_root='data/inshop', mode='query')
>>> inshop_query = InShop(**inshop_query_cfg)
>>> len(inshop_query)
14218
>>> inshop_gallery_cfg = dict(data_root='data/inshop', mode='gallery')
>>> inshop_gallery = InShop(**inshop_gallery_cfg)
>>> len(inshop_gallery)
12612

Checklist

Before PR:

• [ ] Pre-commit or other linting tools are used to fix the potential lint issues.
• [ ] Bug fixes are fully covered by unit tests, the case that causes the bug should be added in the unit tests.
• [ ] The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
• [ ] The documentation has been modified accordingly, like docstring or example tutorials.

After PR:

• [ ] If the modification has potential influence on downstream or other related projects, this PR should be tested with those projects, like MMDet or MMSeg.
• [ ] CLA has been signed and all committers have signed the CLA in this PR.