Fix cpp XE compile issue

[ghost]

• Escape 'register', 'volatile' etc keyword for cpp
• Fix xe compile issue on cpp

[codecov-io]

Codecov Report

Merging #497 into master will decrease coverage by <.01%.
The diff coverage is 73.33%.

@@            Coverage Diff             @@
##           master     #497      +/-   ##
==========================================
- Coverage   84.03%   84.03%   -0.01%     
==========================================
  Files         109      109              
  Lines       13061    13076      +15     
  Branches     1886     1892       +6     
==========================================
+ Hits        10976    10988      +12     
- Misses       1567     1569       +2     
- Partials      518      519       +1

Impacted Files	Coverage Δ
ydkgen/builder/multi_file_builder.py	98.31% <ø> (ø)	⬆️
ydkgen/common.py	79.82% <ø> (ø)	⬆️
generate.py	53.96% <ø> (ø)	⬆️
ydkgen/__init__.py	84.5% <100%> (+0.23%)	⬆️
ydkgen/builder/_api_model_builder.py	86.77% <66.66%> (-0.69%)	⬇️
ydkgen/builder/test_case/test_value_builder.py	92.05% <0%> (-0.84%)	⬇️
...cases/python/expected/ydk/models/ydktest_sanity.py	74.67% <0%> (ø)	⬆️
ydkgen/builder/test_case/test_cases_builder.py	82.01% <0%> (+1.07%)	⬆️

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