kdevelop: added ability to include kdevelop plugins, kdev-php: init at 5.3.1, kdev-python: init at 5.3.1

[aanderse]

Motivation for this change

Added php and python support as optional plugins for kdevelop.

Note: There is a bug upstream which I have submitted a patch for to fix a problem in kdevelop on nixos. See https://invent.kde.org/kde/kdevelop/merge_requests/8 for details. The issue likely won't be resolved in kdevelop before 19.03 so I suggest this PR is merged as is.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Assured whether relevant documentation is up to date
• Fits CONTRIBUTING.md.

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[aanderse]

@GrahamcOfBorg build kdevelop kdev-php kdev-python

[nixos-discourse]

This pull request has been mentioned on Nix community. There might be relevant details there:

https://discourse.nixos.org/t/nixos-19-03-feature-freeze/1950/31