For most SPKGs, the dependencies file contains more accurate information than what can be found in the "Dependencies" section of SPKG.rst.

We simplify the format of the dependencies file by introducing new files dependencies_optional, dependencies_order_only, dependencies_check.

We extend the sage-spkg-info script so that, by simple heuristic text wrangling, the dependencies file is transformed to more human-readable form. When formatting for rst output for the "spkg" chapter of the reference manual, we format the dependencies as hyperlinks.
Example: https://d385f0db7500bdc8168e6f7f18d76741efa3742b--sagemath-tobias.netlify.app/reference/spkg/cvxopt.html#dependencies

Then we remove the redundant "dependencies" sections from the SPKG.rst files.

Depends on #33601

CC: @jhpalmieri @seblabbe @slel @dimpase @videlec @tobiasdiez

Component: build

Keywords: sd111

Author: Matthias Koeppe

Branch/Commit: c359f6b

Reviewer: Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/31017