Go-server parse bool in query parameter

[gmtstephane]

Hi, this PR allow support to boolean values in query parameters.
I change the petstore api example to generate a test case

The commits are pretty self explainatory, i added a function alongside parseInt32Parameter, and update the template in case of boolean value.

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• If contributing template-only or documentation-only changes which will change sample output, build the project beforehand.
• Run the shell script ./bin/generate-samples.shto update all Petstore samples related to your fix. This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master. These must match the expectations made by your contribution. You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*. For Windows users, please run the script in Git BASH.
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[wing328]

Please do not change petstore.yaml.

To have more test cases covered, please switch to https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/test/resources/3_0/petstore-with-fake-endpoints-models-for-testing.yaml instead.

[wing328]

Please resolve the merge conflicts and undo the changes to petstore.yaml when you've time.

[wing328]

I've cherry-pick your commits, resolved the merged conflicts and filed #9171 instead.