Add packs and queries from input

This commit adds the packs and queries from the actions input to the
config file used by the CodeQL CLI.

When the `+` is used, the actions input value is combined with the
config value and when it is not used, the input value overrides the
config value.

This commit also adds a bunch of integration tests for this feature.
In order to avoid adding too many new jobs, all of the tests are
run sequentially in a single job (matrixed across relevant operating
systems and OSes).

.github/check-codescanning-config/index.ts

@@ -0,0 +1,39 @@
+
+import * as core from '@actions/core'
+import * as yaml from 'js-yaml'
+import * as fs from 'fs'
+import * as assert from 'assert'
+
+const actualConfig = loadActualConfig()
+
+const rawExpectedConfig = process.argv[3].trim()
+if (!rawExpectedConfig) {
+  core.info('No expected configuration provided')
+} else {
+  core.startGroup('Expected generated user config')
+  core.info(yaml.dump(JSON.parse(rawExpectedConfig)))
+  core.endGroup()
+}
+
+const expectedConfig = rawExpectedConfig ? JSON.parse(rawExpectedConfig) : undefined;
+
+assert.deepStrictEqual(
+  actualConfig,
+  expectedConfig,
+  'Expected configuration does not match actual configuration'
+);
+
+
+function loadActualConfig() {
+  if (!fs.existsSync(process.argv[2])) {
+    core.info('No configuration file found')
+    return undefined
+  } else {
+    const rawActualConfig = fs.readFileSync(process.argv[2], 'utf8')
+    core.startGroup('Actual generated user config')
+    core.info(rawActualConfig)
+    core.endGroup()
+
+    return yaml.load(rawActualConfig)
+  }
+}