refactor!: [MOBC-701] [MOBC-702] combine deriv_auth_ui with deriv_auth and remove deriv_auth_ui

[ahrar-deriv]

Clickup link:
https://app.clickup.com/t/20696747/MOBC-701
https://app.clickup.com/t/20696747/MOBC-702

This PR contains the following changes:

• combines deriv_auth_ui with deriv_auth
• removes deriv_auth_ui from packages

• ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• ✅ Build configuration change
• 📝 Documentation
• 🗑️ Chore

Pre-launch Checklist (For PR creator)

As a creator of this PR:

• ✍️ I have included clickup id and package/app_name in the PR title.
• 👁️ I have gone through the code and removed any temporary changes (commented lines, prints, debug statements etc.).
• ⚒️ I have fixed any errors/warnings shown by the analyzer/linter.
• 📝 I have added documentation, comments and logging wherever required.
• 🧪 I have added necessary tests for these changes.
• 🔎 I have ensured all existing tests are passing.

Reviewers

@bassam-deriv @behnam-deriv @ernest-deriv

Pre-launch Checklist (For Reviewers)

As a reviewer I ensure that:

• ✴️ This PR follows the standard PR template.
• 🪩 The information in this PR properly reflects the code changes.
• 🧪 All the necessary tests for this PR's are passing.

Pre-launch Checklist (For QA)

• 👌 It passes the acceptance criteria.

Pre-launch Checklist (For Maintainer)

• [MAINTAINER_NAME] I make sure this PR fulfills its purpose.

[bassam-deriv]

@ahrar-deriv I suggest that we just merge this PR for now since it doesn't contain any actual changes to the code and all we did was move everything from deriv_auth_ui to deriv_auth which is technically not a breaking change so no need to keep it opened. Next we create a new PR which contains the actual refactoring of the package which will actually have creaking changes.
I do suggest though to rename the PR from refactor to feat since we're moving a whole feature (the UI) to this package just for the sake of properly versioning it once this PR is merged.

[behnam-deriv]

@ahrar-deriv right now deriv_auth.dart barrel file only exports logic related files. we should add the UI related files also. This way client can just import deriv_auth.dart and have access to logic and UI for authentication and no need for additional import lines.

[bassam-deriv]

@ahrar-deriv Why did you add ! to the PR title?
I don't think this is a breaking change for deriv_auth, and deriv_auth_ui is deleted now so there is no package that needs a breaking change version bump.

[ahrar-deriv]

@ahrar-deriv Why did you add ! to the PR title? I don't think this is a breaking change for deriv_auth, and deriv_auth_ui is deleted now so there is no package that needs a breaking change version bump.

need to bump the major as this is adding a new package ( feat ) in and removing another package, so it is easier to spot in versions also (in tags)