• Move the current functionality of sage -i to sage -p (without any functional changes).
• Add a new implementation for sage -i which installs new-style packages with dependencies.
• Make sage -f equivalent to sage -i -f, which installs dependencies and force-reinstalls a package.

For documentation changes, see #18859.

Depends on #19103
Depends on #19104

CC: @rwst @nathanncohen

Component: scripts

Author: Jeroen Demeyer

Branch: e856a8e

Reviewer: Volker Braun

Issue created by migration from https://trac.sagemath.org/ticket/19101