nix: add nix packaging files

[imincik]

Description

Add Nix packaging files to enable unique Nix features for this project.

This PR will be explained in my QGIS User Conference talk.

[imincik]

@timlinux , you might be interested

[github-actions]

🪟 Windows builds ready!

Windows builds of this PR are available for testing here. Debug symbols for this build are available here.

(Built from commit 1f1d784)

[nyalldawson]

Do these files have to be in the root directory? It'd be cleaner if they were in a subdirectory

[imincik]

Do these files have to be in the root directory? It'd be cleaner if they were in a subdirectory

It is a Nix convention to have them in root directory, but I agree that it might look cleaner to have them in subdirectory. I can move them if people are interested in merging this PR.

[github-actions]

The QGIS project highly values your contribution and would love to see this work merged! Unfortunately this PR has not had any activity in the last 14 days and is being automatically marked as "stale". If you think this pull request should be merged, please check

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  • link to any issues which this pull request fixes

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  In case you should have any uncertainty, please leave a comment and we will be happy to help you proceed with this pull request.
  If there is no further activity on this pull request, it will be closed in a week.

[github-actions]

The QGIS project highly values your contribution and would love to see this work merged! Unfortunately this PR has not had any activity in the last 14 days and is being automatically marked as "stale". If you think this pull request should be merged, please check

• that all unit tests are passing

• that all comments by reviewers have been addressed

• that there is enough information for reviewers, in particular

  • link to any issues which this pull request fixes

  • add a description of workflows which this pull request fixes

  • add screenshots if applicable

• that you have written unit tests where possible
  In case you should have any uncertainty, please leave a comment and we will be happy to help you proceed with this pull request.
  If there is no further activity on this pull request, it will be closed in a week.

[github-actions]

While we hate to see this happen, this PR has been automatically closed because it has not had any activity in the last 21 days. If this pull request should be reconsidered, please follow the guidelines in the previous comment and reopen this pull request. Or, if you have any further questions, just ask! We love to help, and if there's anything the QGIS project can do to help push this PR forward please let us know how we can assist.

[autra]

I'd be in favor of reopening this : it's very handy for nix users, because it allows to build+install qgis from any commits that contains a flake.nix, without ever worrying about compatibilities with system libs.

We can already install old versions from the set of versions known by nixpkgs (for instance, to use qgis 2.18, I'd use nix-shell -p qgis -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/f06d8e0bf4822788f93ed994c4a9e88bda3606c3.tar.gz), but discoverability is not great and this would go a step further by allowing this on every commit, even unreleased one.

I think it'd be very useful for dogfooding and testing, at least.