Users should be able to save GitHub username and repository through the Collabocate (flutter) UI

[Oyebliss]

Issue description

On the mobile app, it is not yet possible for users to specify and save the Github username and repository, that they will like issue reports to go to. We need to create a field where collabo users can input their GitHub profile name and the repository they will like to relate with.

Expected behavior

• There should be 2 fields on the UI where Github username and repository can be entered respectively by the user.
• Incase of error on the input, there should be a display of error message to check if any correction is need.
• To be done on a different page/screen.

Additional context

• Repo URL : https://github.com/collabo-community/collabocate-flutter

Testing checklist

Note (to contributor taking on this task assignment): Add the testing checklist below (without this note) to your pull request when submitting your fix. This will guide (you and) the contributors who will review your fix to know what is important to check or test for.

• An input field for Github username, and an input field for the repository is on the UI.
• The input fields are added on a different page/screen.
• The input fields successfully save to the backend when correct details are entered.
• Meaningful error message is displayed on the UI, if it fails for any reason.
• I certify that I ran my checklist