Upgrade the dependencies and get sdk_refactoring_demo app to a working condition

[purnimavenkatasubbu]

Describe the bug
sdk_refactoring_demo app is not in working condition. We need to upgrade dependencies and issues need to be resolved.

To Reproduce
Steps to reproduce the behavior:

1. Upgrade to the latest dependencies and run the app.

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots
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Smartphone (please complete the following information):

Were you using an @‎application when the bug was found?

• [e.g. @‎ https://github.com/atsign-foundation/at_demos/tree/sdk_refactoring_demo]

Additional context
Add any other context about the problem here.

[purnimavenkatasubbu]

Please re-assign if needed.

[cpswan]

Once this is done can we pin the dependencies, use the pub.dev dependabot to automate PRs for when they change, and automate the build process so that we have something that's keeping up with underlying dependencies to give us warning of any trouble?

@gkc @VJag @murali-shris

[VJag]

Yes @cpswan

[gkc]

@XavierChanth FYI