Add support for -fplugin-package

[phadej]

https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/extending_ghc.html#ghc-flag--plugin-package%20%E2%9F%A8pkg%E2%9F%A9

Unlike -package ⟨pkg⟩, this option does NOT cause package ⟨pkg⟩ to be linked into the resulting executable or shared object.

[tkvogt]

If I remember it correctly, a compiler plugin has to be installed in the global package db.
This unfortunately doesn't work:
sudo -S "PATH=$PATH" /opt/ghc/bin/cabal v1-install --ghc-options="-package-db=/opt/ghc/8.8.1/lib/ghc-8.8.1/package.conf.d"
But how to fix this? What about using the category-field in the cabal file and when it says "compiler plugin" then "cabal install" should automatically install in the global package db. All the old plugins would work again without having to invent a new option to "cabal install": https://hackage.haskell.org/packages/#cat:Compiler%20Plugin

[coot]

It would be nice to support -fplugin-package in such a way that one can specify it in cabal.project.local file. My use case is a parser plugin which does not modify the parsed tree but extracts tags information from it. For this kind of plugins one does not want to add a dependency in a *.cabal file.

Currently if I add:

package mypackage
  ghc-options: -plugin-package ghctags -fplugin=Plugin.GhcTags

source-repository-package
  type: git
  location: /home/coot/repos/haskell/ghctags
  tag: 63ef002ae3383050febcb207d7709ecdf47d2a2b
  subdir: .

without modifying bulid-depends I get the following error:

<command line>: cannot satisfy -package ghctags