Add customize content type blade in iot Explorer

[Elsie4ever]

Add customize content type blade in iot Explorer and related unit tests Current only support protobuf

General Guidelines

• [ ] If introducing new functionality or modified behavior, are they backed by unit tests?
• [ ] Have all unit tests passed locally? (by running npm run test command)
• [ ] Have you updated the README.md with new screenshots if significant changes have been made?
• [ ] Have you update the package version if the current version in package.json is not higher than the version released?