Add availability checks and detailed error handling for video adapters

[dikjain]

• Implemented getAvailabilityInfo method in ExpoAVVideoAdapter and ExpoVideoAdapter to provide detailed error messages and installation commands if the required modules or components are not found.
• Updated renderVideo methods to utilize the new availability checks.
• Added a simple getAvailabilityInfo method in FallbackVideoAdapter for consistency.
• Updated VideoPlayerAdapter interface to include the new method for availability information.

Brief Summary of Changes

Replaced vague "expo-av/expo-video is not available" error messages with clear, actionable error messages that include specific installation commands. The new getAvailabilityInfo() method provides structured error information including the missing package name, descriptive error message, and exact installation command to resolve the issue.

What does this PR address?

• Fix ExpoAVVideoAdapter error handling - provide clear guidance when expo-av missing #55 GitHub issue (Add reference - #XX)
• Refactoring
• New feature
• Bug fix
• Adds more tests

Are tests included?

• Yes
• No

Reviewer, please note:

nothing as such, since it's a simlple fix

• This is a minimal, backwards-compatible change that only improves error messaging
• The new getAvailabilityInfo() method follows the existing adapter pattern
• All existing tests continue to pass without modification

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I ran the full test suite before pushing the changes and all the tests pass.