[5.x] Select specific repositories for Eloquent Driver install command

[kevinmeijer97]

Adds --repositories option to statamic:install:eloquent-driver command, allowing targeted repository migration via comma-separated list.

Key improvements:

• Supports selective repository migration without manual selection
• Validates and normalizes repository names
• Provides warning for invalid repository inputs
• Maintains existing multiselect and --all functionality

Example usage:

php artisan statamic:install:eloquent-driver --repositories=assets,entries,forms

[duncanmcclean]

Thank you for this PR!

I've made a couple of changes:

• The command will now error out when one of the specified repositories is invalid.
• The command will show a warning when one of the specified repositories is already driven by the Eloquent Driver.
• I've also done a little bit of refactoring to separate the list of "all repos" from the list of "available" repos.