chore(sdk): update cli v2 code

[connor-mccarthy]

Description of your changes:
Note: do not merge before #7547.

This PR layers in changes on top of the original V1 CLI port.

Major changes:

• remove typer framework from CLI
• use __main__.py as CLI entrypoint
• make logging about --engine flag more clear in kfp component build command (docker is
  the only engine supported)
• simplify diagnose_me command code (no functional change)
• adds mypy.ini file to silence unresolvable mypy error

Minor changes:

• remove unused imports
• sort imports
• update type hints
• update copyright
• remove unnecessary linting comments
• idiomatic python refactorings

Checklist:

• The title for your pull request (PR) should follow our title convention. Learn more
  about the pull request title convention used in this repository.

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[connor-mccarthy]

/test all

[connor-mccarthy]

/test all