main/postmarketos-base: pmb_recommends: add doas-sudo-shim

Fix the following error during "pmbootstrap install":

  ERROR: unable to select packages:
    sudo-1.9.16_p1-r1:
      conflicts: doas-sudo-shim-0.1.1-r1[cmd:sudo=1.9.16_p1-r1]
      breaks: doas-sudo-shim-0.1.1-r1[!sudo]
      satisfies: postmarketos-base-38-r0[sudo-virt]
                 postmarketos-base-nofde-38-r0[sudo-virt]
    doas-sudo-shim-0.1.1-r1:
      conflicts: sudo-1.9.16_p1-r1[cmd:sudo=0.1.1-r1]
      satisfies: postmarketos-base-doas-38-r0[doas-sudo-shim]
                 postmarketos-base-38-r0[sudo-virt]
                 postmarketos-base-nofde-38-r0[sudo-virt]

How the error gets triggered:

• postmarketos-base depends on sudo-virt. During "pmbootstrap install", pmbootstrap has to resolve this to a sudo implementation (sudo, doas, ...).
• pmbootstrap does this by looking at the packages that get installed at the same time. Before this patch we did not install doas-sudo-shim directly through _pmb_recommends, only indirectly through a postmarketos-base-doas subpackage that pulls doas-sudo-shim in via install_if.
• pmbootstrap cannot look at install_if as it resolves dependencies, so it has to pick one and goes for "sudo".
• pmbootstrap tells apk to install a list of packages including "sudo", and because apk also resolves install_if correctly, the solver fails at the conflict between "doas-sudo-shim" and "sudo". (This only fails since apk-tools-static 2.14.6-r0, apparently beforehand apk just installed "doas-sudo-shim" in this scenario.)

Teaching pmbootstrap to look at install_if while resolving packages would be one way to fix this. But it would be a lot of effort, not feasible to quickly stop the problem at hand that breaks "pmbootstrap install" for all edge installs. IMHO it is not worth implementing this at all in pmbootstrap, as it is just supposed to do some more or less basic package resolving until apk takes over and does it properly.

Put doas-sudo-shim in _pmb_recommends so pmbootstrap knows that this is the sudo implementation we want without looking at install_if.

Remove the now obsolete postmarketos-base-doas subpackage. This will lead to doas-sudo-shim getting removed for old installations on upgrade, but it can easily be installed back (doas add doas-sudo-shim). I'll make an edge post about it and put it in the v24.12 release notes. If we don't remove it here, we would need to keep this legacy subpackage around forever and I'd rather avoid that to reduce maintenance effort.

Another alternative to this was removing sudo-virt from depends="". But that would lead to sudo getting uninstalled for users upgrading from old releases from before we had doas in pmb_recommends, so I've decided against it.

Fix #3340 (closed)