Introduce the project:convert command

[akalipetis]

The project:convert command is meant to be used for converting other types of configuration to Upsun, currently supporting only the platformsh provider.

Command: project:convert
Description: Generate an Upsun compatible configuration based on the configuration from another provider.

Usage:
 upsun project:convert

Options:
  -h, --help           Display this help message
  -v|vv|vvv, --verbose Increase the verbosity of messages
  -V, --version        Display this application version
  -y, --yes            Answer "yes" to confirmation questions; accept the default value for other questions; disable interaction
      --no-interaction Do not ask any interactive questions; accept default values. Equivalent to using the environment variable: UPSUN_CLI_NO_INTERACTION=1
  -p, --provider       The provider from which to convert the configuration. Currently, only 'platformsh' is supported.

Examples:
 Convert the Platform.sh project configuration files in your current directory:
   upsun project:convert --provider=platformsh

[Copilot]

Pull Request Overview

This PR introduces a new project:convert command to convert configuration files from other providers to Upsun format. Currently supports converting Platform.sh configurations to Upsun format.

• Adds the project:convert command with Platform.sh to Upsun conversion capability
• Integrates the command into the CLI framework with proper help documentation and examples
• Adds dependency on github.com/upsun/lib-sun library for conversion logic

Reviewed Changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 2 comments.

File	Description
go.mod	Adds lib-sun dependency for conversion functionality
commands/root.go	Adds yes flag and conditionally registers convert command for Upsun flavor
commands/list.go	Adds convert command to the list output for Upsun configurations
commands/convert_config.go	Implements the complete convert command with Platform.sh to Upsun conversion logic

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