Camel case backward compatible in Swagger doc

[xin-au]

Hi @johanbrandhorst,
In the PR, #985, the snake case arguments will be converted to lower camel case when the json_names_for_fields is enabled.
Now, I noticed that there is a backward compatible use case may need to support, which is / could be inside {}, for example, "/{user.name=prefix/*}:customMethod". (Sorry I did not notice that)
Also, when calculating jsonSnakeCaseName, if the name includes /, then it could cause out of range potentially. So, fixed it too.
Sorry for about.

[codecov-io]

Codecov Report

Merging #988 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #988      +/-   ##
==========================================
+ Coverage   53.43%   53.45%   +0.01%     
==========================================
  Files          40       40              
  Lines        4027     4028       +1     
==========================================
+ Hits         2152     2153       +1     
  Misses       1676     1676              
  Partials      199      199

Impacted Files	Coverage Δ
protoc-gen-swagger/genswagger/template.go	54.27% <100%> (+0.04%)	⬆️

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[johanbrandhorst]

Do these new tests cover the case that caused an index out of range error too?

[xin-au]

@johanbrandhorst , yes, it covered the test case (/ inside {})
In TestFQMNtoSwaggerName and TestTemplateToSwaggerPath with enabling SetUseJSONNamesForFields by setting it as true, which means to enable the JSON camle case, otherwise it is false by default. The following links are the tests with SetUseJSONNamesForFields(true)
https://github.com/grpc-ecosystem/grpc-gateway/pull/988/files#diff-20461b822a903046234d0fa5073ba2c4R924
https://github.com/grpc-ecosystem/grpc-gateway/pull/988/files#diff-20461b822a903046234d0fa5073ba2c4R1009

[johanbrandhorst]

Thanks for your contribution!

[xin-au]

Thank you so much @johanbrandhorst !