[Service] Websockect server and client for SMPL(X) verts inference

[LazyBusyYang]

1. Add a base class for flask http server, a builder for servers and a tool for starting a server.
2. Add a subclass SMPLStreamService for smpl(x) verts inference, and its python websocket client.
3. Add a dockerfile for server.
4. Add a class SMPLStreamClient , tested on Linux and Windows.

[codecov-commenter]

Codecov Report

Merging #125 (73a41c3) into main (32e7ddc) will decrease coverage by 2.52%.
Report is 4 commits behind head on main.
The diff coverage is 4.62%.

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@@            Coverage Diff             @@
##             main     #125      +/-   ##
==========================================
- Coverage   61.19%   58.68%   -2.52%     
==========================================
  Files         178      185       +7     
  Lines       11097    11608     +511     
==========================================
+ Hits         6791     6812      +21     
- Misses       4306     4796     +490     

Flag	Coverage Δ
unittests	58.68% <4.62%> (-2.52%)	⬇️

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

Files Changed	Coverage Δ
xrmocap/client/__init__.py	0.00% <0.00%> (ø)
xrmocap/client/smpl_verts_client.py	0.00% <0.00%> (ø)
...cap/data/data_converter/panoptic_data_converter.py	77.23% <ø> (ø)
xrmocap/service/base_flask_service.py	0.00% <0.00%> (ø)
xrmocap/service/builder.py	0.00% <0.00%> (ø)
xrmocap/service/smpl_verts_service.py	0.00% <0.00%> (ø)
xrmocap/utils/date_utils.py	0.00% <0.00%> (ø)
xrmocap/utils/service_utils.py	0.00% <0.00%> (ø)
...p/data/data_converter/humman_smc_data_converter.py	14.28% <14.28%> (ø)
xrmocap/data/data_converter/builder.py	100.00% <100.00%> (ø)

... and 2 files with indirect coverage changes

[yl-1993]

As discussed offline, we may rename SMPLVertsService to SMPLStreamServer, where Stream indicates that the vertices of SMPL are not stored but instead directly forwarded to viewer server.