Configure Renovate (#1633)

* Add renovate.json

* Move Renovate Bot configuration to .github directory

This is allowed according to the documentation[1] and makes more sense 
in my opinion as it is something that is relevant exclusively on GitHub.

--
1. https://docs.renovatebot.com/configuration-options/

* Specify labels to be used by PRs from Renovate Bot

as per: https://docs.renovatebot.com/configuration-options/#labels

* Schedule Renovate Bot to run once a month

as per 
https://docs.renovatebot.com/presets-config/#configsemverallmonthly

* Separate lockFileMaintenance configuration

based on 
https://docs.renovatebot.com/presets-default/#maintainlockfilesmonthly

* Refine schedule to bi-weekly

* Refactor the Renovate Bot configuration file

* Convert the Renovate bot configuration file to the JSON5 format

Which is allowed as per [1], for details see [2].

Specifically utilizing the fact that keys don't need qoutes, trailing 
commas (,) are allowed, and comments can be used.

--
1. https://docs.renovatebot.com/configuration-options/
2. https://json5.org/

* Remove explicit commitMessageAction from Renovate configuration

.github/renovate.json5

@@ -0,0 +1,30 @@
+{
+  extends: [
+    "config:base",
+
+    // Make sure we get a single PR combining all updates
+    "group:all",
+  ],
+
+  lockFileMaintenance: {
+    extends: [
+      // Make sure we get a single PR combining all updates
+      "group:all",
+    ],
+
+    // Explicitly enable lockfile maintenance
+    enabled: true,
+
+    // This schedule should be the same as the general schedule!
+    schedule: "on the 2nd and 4th day instance on sunday after 11pm",
+  },
+
+  // Use our labelling system
+  labels: ["dependencies"],
+
+  // Schedule the PRs to interleave with our release schedule
+  schedule: "on the 2nd and 4th day instance on sunday after 11pm",
+
+  // We generally always want the major version
+  separateMajorMinor: false,
+}