Add language tab custom name support

[oesukam]

Description

This PR adds the language tab custom name feature if you want to have a different name displayed then the supported language as provided in slate

How to test the functionality

1. Clone the repo
2. Have the language_tabs block listed as follow:

        language_tabs:
         - javascript: Web
         - shell

3. Install the dependencies: npm install
4. Run the app: npm run start

Screenshot