We introduce a reusable workflow docker.yml.

After #34017, tox.yml only contains Linux builds, so we rename it to ci-linux.yml and factor it through docker.yml.

We leave tox-optional.yml, tox-experimental.yml as is for a follow-up ticket (#33062).

We also add two new platforms and remove two platforms that can no longer be tested.

Test run: https://github.com/mkoeppe/sage/actions/runs/2748565810

The workflow docker.yml can also be used by upstream packages. First example: https://github.com/latte-int/latte/blob/master/.github/workflows/ci-sage.yml (ran at https://github.com/latte-int/latte/actions/runs/2633447828)

Depends on #34017
Depends on #33800
Depends on #29549
Depends on #33791

CC: @dimpase @kliem

Component: porting

Author: Matthias Koeppe

Branch/Commit: a3d2200

Reviewer: Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/34115