[cc] [workflow] Add C backend to Github CI

[archibate]

Related issue = #1332 #1644

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[codecov]

Codecov Report

Merging #1643 into master will decrease coverage by 0.65%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #1643      +/-   ##
==========================================
- Coverage   45.06%   44.40%   -0.66%     
==========================================
  Files          40       41       +1     
  Lines        5790     5876      +86     
  Branches     1012     1022      +10     
==========================================
  Hits         2609     2609              
- Misses       3032     3118      +86     
  Partials      149      149              

Impacted Files	Coverage Δ
python/taichi/cc_compose.py	0.00% <0.00%> (ø)
python/taichi/core/util.py	0.29% <0.00%> (-0.01%)	⬇️
python/taichi/main.py	23.73% <0.00%> (-0.40%)	⬇️
python/taichi/testing.py	76.92% <ø> (ø)

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[archibate]

Merging since:
All the CIs are passing.
I added the continue-on-error option in case CC fails, it won't break CI completely.
This PR also emergency OFT fix cc_compose.py.