feat : Added Basic Authorization in API request

[maiHydrogen]

PR Description

Added Basic Authorization method for both rest and graphql apis by directly injecting the authorization header into the sendhttprequest method without making any changes in existing httprequest model because of thier freezed nature and this method provides more scope for scalability for future auth methods.

Related Issues

• Closes Add API Auth: Basic authentication #610

Screenshots

Checklist

• I have gone through the contributing guide
• I have updated my branch and synced it with project main branch before making this PR
• I am using the latest Flutter stable branch (run flutter upgrade and verify)
• I have run the tests (flutter test) and all melos tests are passing

Added/updated tests?

We encourage you to add relevant test cases.

• Yes
• No, and this is why: I wanted to but i didn't know how to that is why I couldn't add them.

OS on which you have developed and tested the feature?

• Windows
• macOS
• Linux