[mesheryctl] Enhance context and start commands with --provider flag

[leecalcote]

See mesheryctl Command Tracker for current status of commands.

Current Behavior

Without editing their meshconfig, users are unable to specify the name of the Provider (e.g. Local, Meshery).

Desired Behavior

Enhance mesheryctl system start and mesheryctl system context create to support specification of the Provider name using a --provider flag.

Acceptance Tests

1. Users can assign provider per context.
2. Users can assign provider as an environment variable prior to start of Meshery container.
3. Users can assign provider when creating a context using mesheryctl.
4. Users can assign provider when deploying a Meshery instance when using system start using mesheryctl.

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Contributor Resources

• ⌨️ mesheryctl Contributing Guide
• Beginner's guide to contributing to Meshery and mesheryctl
• mesheryctl Command Tracker
• Meshery CLI Commands and Documentation
• 🙋🏾🙋🏼 Questions: Discussion Forum and Community Slack

[github-actions]

This issue has been labeled with 'component/mesheryctl'. Note that after making changes you need to update it in the mesheryctl command tracker spreadsheet.

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