Feature: opt-in survey when exiting a game

On first start-up, the game will ask if you want to participate
in our automated survey. You have to opt-in, and can easily opt-out
(via the Options) at any time.

When opt-in, whenever you exit a game, a JSON blob will be send
to the survey server hosted by OpenTTD. This JSON blob contains
information that gives a global picture of the game just played:
- What settings were used
- How many humans vs AIs
- How long the game has been played
- Basic information about the OS / CPU

All this information is kept very generic, so there is no
chance we send private information to our survey server.
Nothing in the JSON blob could identify you as a person; it
mostly tells about the game played. At any time you can see
what the JSON blob includes, by pressing the "Preview Survey
Results" button in-game.

.github/workflows/release.yml

@@ -38,6 +38,9 @@ jobs:
     uses: ./.github/workflows/release-linux.yml
     secrets: inherit
 
+    with:
+      survey_key: ${{ needs.source.outputs.survey_key }}
+
   macos:
     name: MacOS
     needs: source
@@ -45,6 +48,9 @@ jobs:
     uses: ./.github/workflows/release-macos.yml
     secrets: inherit
 
+    with:
+      survey_key: ${{ needs.source.outputs.survey_key }}
+
   windows:
     name: Windows
     needs: source
@@ -54,6 +60,7 @@ jobs:
 
     with:
       is_tag: ${{ needs.source.outputs.is_tag }}
+      survey_key: ${{ needs.source.outputs.survey_key }}
 
   windows-store:
     name: Windows Store