[Feature] Kernel iter head

[FANG-MING]

trafficstars

Thanks for your contribution and we appreciate it a lot. The following instructions would make your pull request more healthy and more easily get feedback. If you do not understand some items, don't worry, just make the pull request and seek help from maintainers.

Motivation

Add kernel_iter_head which is a roi head in K-Net

Modification

support K-Net

Checklist

1. Pre-commit or other linting tools are used to fix the potential lint issues.
2. The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
3. If the modification has potential influence on downstream projects, this PR should be tested with downstream projects, like MMDet or MMCls.
4. The documentation has been modified accordingly, like docstring or example tutorials.

[CLAassistant]

All committers have signed the CLA.

[codecov[bot]]

Codecov Report

Merging #7639 (3e26931) into dev (6b87ac2) will increase coverage by 0.68%. The diff coverage is 81.75%.

:exclamation: Current head 3e26931 differs from pull request most recent head cee627d. Consider uploading reports for the commit cee627d to get more accurate results

@@            Coverage Diff             @@
##              dev    #7639      +/-   ##
==========================================
+ Coverage   63.41%   64.10%   +0.68%     
==========================================
  Files         340      346       +6     
  Lines       27493    28117     +624     
  Branches     4645     4744      +99     
==========================================
+ Hits        17436    18024     +588     
- Misses       9131     9150      +19     
- Partials      926      943      +17     

Flag	Coverage Δ
unittests	64.07% <81.75%> (+0.68%)	:arrow_up:

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

Impacted Files	Coverage Δ
mmdet/apis/test.py	12.50% <0.00%> (-0.90%)	:arrow_down:
mmdet/core/bbox/assigners/max_iou_assigner.py	73.68% <ø> (+1.31%)	:arrow_up:
mmdet/core/post_processing/bbox_nms.py	79.10% <ø> (ø)
mmdet/core/utils/__init__.py	100.00% <ø> (ø)
mmdet/datasets/pipelines/instaboost.py	15.00% <0.00%> (ø)
...mdet/models/dense_heads/free_anchor_retina_head.py	16.00% <0.00%> (-0.22%)	:arrow_down:
mmdet/models/dense_heads/ssd_head.py	85.84% <ø> (ø)
mmdet/models/necks/fpn.py	94.66% <ø> (ø)
mmdet/core/utils/dist_utils.py	23.59% <15.38%> (-1.41%)	:arrow_down:
mmdet/utils/misc.py	64.10% <22.22%> (-35.90%)	:arrow_down:
... and 46 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 6b87ac2...cee627d. Read the comment docs.

[ZwwWayne]

Need to resolve conflicts and update the code, clean unnecessary code.