Rename option name force_orphan to keep_history

[peaceiris]

trafficstars

Is your feature request related to a problem? Please describe

- force_orphan: true
+ keep_history: false  # default is true

Describe the solution you'd like

• Add keep_history option to v3
• Remove force_orphan in v4

Describe alternatives you've considered

N/A.

Additional context

N/A.

[peaceiris]

Anything else confusing users? (option names, documents, and so on.)

[privatenumber]

Nitpicky but what do you think of preserve_commit_history?

[istudyatuni]

One else suggestion: single-commit like here