Implement Tech Insights backend

* Add common types and interfaces for Tech Insights. Exposing components needed to use and modify tech-insights-backend module and to implement individual Fact Retrievers, Fact Checkers and their persistence options.

* Implement a framework to run fact retrievers and store fact data into the database. Add migration scripts to create a new database for `tech_insights`.

* Create a default implementation of a FactChecker enabling users to construct checks and run them and generate scorecards based on checks.

* To be able to use tech insights in your application you need to implement `FactRetriever`s to retrieve and return data for facts and register them to the tech-insights-backend. If you want to use fact checking functionality, you need to create `check`s and register them to an implementation of a `FactChecker`.

For more information see documentation on the README.md files of the respective packages.

Signed-off-by: Jussi Hallila <jussi@hallila.com>

plugins/tech-insights-common/package.json

@@ -0,0 +1,45 @@
+{
+  "name": "@backstage/plugin-tech-insights-common",
+  "version": "0.1.0",
+  "main": "src/index.ts",
+  "types": "src/index.ts",
+  "license": "Apache-2.0",
+  "private": false,
+  "publishConfig": {
+    "access": "public",
+    "main": "dist/index.cjs.js",
+    "types": "dist/index.d.ts"
+  },
+  "homepage": "https://backstage.io",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/backstage/backstage",
+    "directory": "plugins/tech-insights-common"
+  },
+  "keywords": [
+    "backstage",
+    "tech-insights"
+  ],
+  "scripts": {
+    "start": "backstage-cli backend:dev",
+    "build": "backstage-cli backend:build",
+    "lint": "backstage-cli lint",
+    "test": "backstage-cli test",
+    "prepack": "backstage-cli prepack",
+    "postpack": "backstage-cli postpack",
+    "clean": "backstage-cli clean"
+  },
+  "dependencies": {
+    "@backstage/backend-common": "^0.9.0",
+    "@backstage/config": "^0.1.8",
+    "@types/luxon": "^2.0.5",
+    "luxon": "^2.0.2",
+    "winston": "^3.2.1"
+  },
+  "devDependencies": {
+    "@backstage/cli": "^0.7.1"
+  },
+  "files": [
+    "dist"
+  ]
+}