feature: Docker OAuth block support (via #4987)

* add `onFound` callback to schemas
* add warning to method docs (for #4957)
* implement Docker OAuth2 init block support
* update docs
* add OAUTH_SCOPE_SEPARATOR
* drop OAuth env from Dockerfile and run script
* don't indent the first oauth block line
* drop unused `dedent` import
* touch up warning message
* add more test cases
* return an empty block if no OAuth content is generated
* fix broken doc line

docker/configurator/helpers.js

@@ -0,0 +1,13 @@
+module.exports.indent = function indent(str, len, fromLine = 0) {
+
+  return str
+    .split("\n")
+    .map((line, i) => {
+      if (i + 1 >= fromLine) {
+        return `${Array(len + 1).join(" ")}${line}`
+      } else {
+        return line
+      }
+    })
+    .join("\n")
+}