V4 Azure functions + few tweaks

Created by: Abrhm7786

Updated generator to V4 Azure functions by default. Also fixed a couple of issues which were preventing the function app from working. Removed "HTTP" prefix from the method type and removed leading forward slashes which were occurring in the path parameter. (This was addressed in earlier changes for "apiPath" parameter but they were also occurring in "path".)

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.
• Run the following to build the project and update samples:

  ./mvnw clean package 
  ./bin/generate-samples.sh
  ./bin/utils/export_docs_generators.sh

  Commit all changed files. 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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