[Feature] Support DaViT

[okotaku]

Motivation

paper: https://arxiv.org/abs/2204.03645
code: https://github.com/dingmyu/davit

#1096

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.

[codecov]

Codecov Report

Base: 0.02% // Head: 91.17% // Increases project coverage by +91.15% 🎉

Coverage data is based on head (3a246f2) compared to base (b8b31e9).
Patch has no changes to coverable lines.

❗ Current head 3a246f2 differs from pull request most recent head 8616e5f. Consider uploading reports for the commit 8616e5f to get more accurate results

Additional details and impacted files

@@             Coverage Diff              @@
##           dev-1.x    #1105       +/-   ##
============================================
+ Coverage     0.02%   91.17%   +91.15%     
============================================
  Files          121      131       +10     
  Lines         8217    10055     +1838     
  Branches      1368     1574      +206     
============================================
+ Hits             2     9168     +9166     
+ Misses        8215      675     -7540     
- Partials         0      212      +212     

Flag	Coverage Δ
unittests	91.17% <ø> (+91.15%)	⬆️

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

Impacted Files	Coverage Δ
mmcls/apis/inference.py	0.00% <0.00%> (ø)
mmcls/datasets/transforms/compose.py
mmcls/models/backbones/efficientformer.py	95.08% <0.00%> (ø)
mmcls/models/backbones/mvit.py	92.46% <0.00%> (ø)
mmcls/models/backbones/deit3.py	94.52% <0.00%> (ø)
mmcls/models/backbones/mobileone.py	94.47% <0.00%> (ø)
mmcls/models/backbones/swin_transformer_v2.py	89.47% <0.00%> (ø)
mmcls/models/utils/layer_scale.py	86.66% <0.00%> (ø)
mmcls/models/heads/efficientformer_head.py	93.10% <0.00%> (ø)
mmcls/structures/utils.py	77.77% <0.00%> (ø)
... and 121 more

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